diff --git a/apps/block_scout_web/assets/js/lib/history_chart.js b/apps/block_scout_web/assets/js/lib/history_chart.js
index fcaa3aa421..f1463cf096 100644
--- a/apps/block_scout_web/assets/js/lib/history_chart.js
+++ b/apps/block_scout_web/assets/js/lib/history_chart.js
@@ -4,7 +4,6 @@ import humps from 'humps'
 import numeral from 'numeral'
 import { formatUsdValue } from '../lib/currency'
 import sassVariables from '../../css/app.scss'
-import { showLoader } from '../lib/utils'
 
 const config = {
   type: 'line',
@@ -104,25 +103,13 @@ function getMarketCapData (marketHistoryData, availableSupply) {
   }
 }
 
-// colors for light and dark theme
-var priceLineColor
-var mcapLineColor
-if (localStorage.getItem('current-color-mode') === 'dark') {
-  priceLineColor = sassVariables.darkprimary
-  mcapLineColor = sassVariables.darksecondary
-} else {
-  priceLineColor = sassVariables.dashboardLineColorPrice
-  mcapLineColor = sassVariables.dashboardLineColorMarket
-}
-
 class MarketHistoryChart {
   constructor (el, availableSupply, marketHistoryData, dataConfig) {
-
-    var axes = config.options.scales.yAxes.reduce(function(solution, elem){
+    var axes = config.options.scales.yAxes.reduce(function (solution, elem) {
       solution[elem.id] = elem
       return solution
     },
-                                                  {})
+    {})
 
     this.price = {
       label: window.localized['Price'],
@@ -130,13 +117,13 @@ class MarketHistoryChart {
       data: [],
       fill: false,
       pointRadius: 0,
-      backgroundColor: priceLineColor,
-      borderColor: priceLineColor,
+      backgroundColor: sassVariables.dashboardLineColorPrice,
+      borderColor: sassVariables.dashboardLineColorPrice,
       lineTension: 0
     }
-    if (dataConfig.market == undefined || dataConfig.market.indexOf("price") == -1){
+    if (dataConfig.market === undefined || dataConfig.market.indexOf('price') === -1) {
       this.price.hidden = true
-      axes["price"].display = false
+      axes['price'].display = false
     }
 
     this.marketCap = {
@@ -145,13 +132,13 @@ class MarketHistoryChart {
       data: [],
       fill: false,
       pointRadius: 0,
-      backgroundColor: mcapLineColor,
-      borderColor: mcapLineColor,
+      backgroundColor: sassVariables.dashboardLineColorMarket,
+      borderColor: sassVariables.dashboardLineColorMarket,
       lineTension: 0
     }
-    if (dataConfig.market == undefined || dataConfig.market.indexOf("market_cap") == -1){
+    if (dataConfig.market === undefined || dataConfig.market.indexOf('market_cap') === -1) {
       this.marketCap.hidden = true
-      axes["marketCap"].display = false
+      axes['marketCap'].display = false
     }
 
     this.numTransactions = {
@@ -162,15 +149,14 @@ class MarketHistoryChart {
       pointRadius: 0,
       backgroundColor: sassVariables.dashboardLineColorMarket,
       borderColor: sassVariables.dashboardLineColorTransactions,
-      lineTension: 0,
+      lineTension: 0
     }
-    if (dataConfig.transactions == undefined || dataConfig.transactions.indexOf("transactions_per_day") == -1){
+    if (dataConfig.transactions === undefined || dataConfig.transactions.indexOf('transactions_per_day') === -1) {
       this.numTransactions.hidden = true
-      axes["numTransactions"].display = false
+      axes['numTransactions'].display = false
     }
 
     this.availableSupply = availableSupply
-    //TODO: This is where we dynamically append datasets
     config.data.datasets = [this.price, this.marketCap, this.numTransactions]
     this.chart = new Chart(el, config)
   }
@@ -185,9 +171,9 @@ class MarketHistoryChart {
     }
     this.chart.update()
   }
-  updateTransactionHistory (transaction_history) {
-    this.numTransactions.data = transaction_history.map(dataPoint => {
-      return {x:dataPoint.date, y:dataPoint.number_of_transactions}
+  updateTransactionHistory (transactionHistory) {
+    this.numTransactions.data = transactionHistory.map(dataPoint => {
+      return {x: dataPoint.date, y: dataPoint.number_of_transactions}
     })
     this.chart.update()
   }
@@ -198,28 +184,24 @@ export function createMarketHistoryChart (el) {
   const dataConfig = $(el).data('history_chart_config')
 
   const $chartLoading = $('[data-chart-loading-message]')
-
-  const isTimeout = true
-  const timeoutID = showLoader(isTimeout, $chartLoading)
-
   const $chartError = $('[data-chart-error-message]')
   const chart = new MarketHistoryChart(el, 0, [], dataConfig)
-  Object.keys(dataPaths).forEach(function(history_source){
-    $.getJSON(dataPaths[history_source], {type: 'JSON'})
+  Object.keys(dataPaths).forEach(function (historySource) {
+    $.getJSON(dataPaths[historySource], {type: 'JSON'})
       .done(data => {
-        switch(history_source){
-        case "market":
-          const availableSupply = JSON.parse(data.supply_data)
-          const marketHistoryData = humps.camelizeKeys(JSON.parse(data.history_data))
-          $(el).show()
-          chart.updateMarketHistory(availableSupply, marketHistoryData)
-          break;
-        case "transaction":
-          const transaction_history = JSON.parse(data.history_data)
-
-          $(el).show()
-          chart.updateTransactionHistory(transaction_history)
-          break;
+        switch (historySource) {
+          case 'market':
+            const availableSupply = JSON.parse(data.supply_data)
+            const marketHistoryData = humps.camelizeKeys(JSON.parse(data.history_data))
+            $(el).show()
+            chart.updateMarketHistory(availableSupply, marketHistoryData)
+            break
+          case 'transaction':
+            const transactionHistory = JSON.parse(data.history_data)
+
+            $(el).show()
+            chart.updateTransactionHistory(transactionHistory)
+            break
         }
       })
       .fail(() => {
@@ -227,8 +209,9 @@ export function createMarketHistoryChart (el) {
       })
       .always(() => {
         $chartLoading.hide()
-      })})
-  return chart;
+      })
+  })
+  return chart
 }
 
 $('[data-chart-error-message]').on('click', _event => {
diff --git a/apps/block_scout_web/assets/js/pages/chain.js b/apps/block_scout_web/assets/js/pages/chain.js
index bb9625b282..8a71893171 100644
--- a/apps/block_scout_web/assets/js/pages/chain.js
+++ b/apps/block_scout_web/assets/js/pages/chain.js
@@ -1,3 +1,4 @@
+/* global _ */
 import $ from 'jquery'
 import omit from 'lodash/omit'
 import first from 'lodash/first'
@@ -9,7 +10,7 @@ import numeral from 'numeral'
 import socket from '../socket'
 import { exchangeRateChannel, formatUsdValue } from '../lib/currency'
 import { createStore, connectElements } from '../lib/redux_helpers.js'
-import { batchChannel, showLoader } from '../lib/utils'
+import { batchChannel } from '../lib/utils'
 import listMorph from '../lib/list_morph'
 import { createMarketHistoryChart } from '../lib/history_chart'
 
@@ -107,9 +108,9 @@ function baseReducer (state = initialState, action) {
         })
       }
     }
-    case 'RECIEVED_UPDATED_TRANSACTION_STATS':{
+    case 'RECIEVED_UPDATED_TRANSACTION_STATS': {
       return Object.assign({}, state, {
-        transactionStats: action.msg.stats,
+        transactionStats: action.msg.stats
       })
     }
     case 'START_TRANSACTIONS_FETCH':
@@ -154,7 +155,7 @@ const elements = {
       if (chart && !(oldState.availableSupply === state.availableSupply && oldState.marketHistoryData === state.marketHistoryData) && state.availableSupply) {
         chart.updateMarketHistory(state.availableSupply, state.marketHistoryData)
       }
-      if (chart && !(_.isEqual(oldState.transactionStats, state.transactionStats))){ 
+      if (chart && !(_.isEqual(oldState.transactionStats, state.transactionStats))) {
         chart.updateTransactionHistory(state.transactionStats)
       }
     }
@@ -223,7 +224,11 @@ const elements = {
   },
   '[data-selector="chain-block-list"] [data-selector="loading-message"]': {
     render ($el, state, oldState) {
-      showLoader(state.blocksLoading, $el)
+      if (state.blocksLoading) {
+        $el.show()
+      } else {
+        $el.hide()
+      }
     }
   },
   '[data-selector="transactions-list"] [data-selector="error-message"]': {
@@ -233,7 +238,7 @@ const elements = {
   },
   '[data-selector="transactions-list"] [data-selector="loading-message"]': {
     render ($el, state, oldState) {
-      showLoader(state.transactionsLoading, $el)
+      $el.toggle(state.transactionsLoading)
     }
   },
   '[data-selector="transactions-list"]': {
diff --git a/apps/block_scout_web/lib/block_scout_web/controllers/chain/transaction_history_chart_controller.ex b/apps/block_scout_web/lib/block_scout_web/controllers/chain/transaction_history_chart_controller.ex
index ca1346ba56..9b1649baba 100644
--- a/apps/block_scout_web/lib/block_scout_web/controllers/chain/transaction_history_chart_controller.ex
+++ b/apps/block_scout_web/lib/block_scout_web/controllers/chain/transaction_history_chart_controller.ex
@@ -5,17 +5,19 @@ defmodule BlockScoutWeb.Chain.TransactionHistoryChartController do
 
   def show(conn, _params) do
     with true <- ajax?(conn) do
-      [{:history_size, history_size}]  = Application.get_env(:block_scout_web, __MODULE__, 30)
+      [{:history_size, history_size}] = Application.get_env(:block_scout_web, __MODULE__, 30)
 
       latest = Date.utc_today()
       earliest = Date.add(latest, -1 * history_size)
 
-      transaction_history_data = TransactionStats.by_date_range(earliest, latest)
+      date_range = TransactionStats.by_date_range(earliest, latest)
+
+      transaction_history_data = date_range
       |> extract_history
       |> encode_transaction_history_data
 
       json(conn, %{
-        history_data: transaction_history_data,
+        history_data: transaction_history_data
       })
     else
       _ -> unprocessable_entity(conn)
@@ -24,7 +26,8 @@ defmodule BlockScoutWeb.Chain.TransactionHistoryChartController do
 
   defp extract_history(db_results) do
     Enum.map(db_results, fn row ->
-      %{date: row.date, number_of_transactions: row.number_of_transactions} end)
+      %{date: row.date, number_of_transactions: row.number_of_transactions}
+    end)
   end
 
   defp encode_transaction_history_data(transaction_history_data) do
diff --git a/apps/block_scout_web/lib/block_scout_web/controllers/chain_controller.ex b/apps/block_scout_web/lib/block_scout_web/controllers/chain_controller.ex
index d5e11ad302..12b440f713 100644
--- a/apps/block_scout_web/lib/block_scout_web/controllers/chain_controller.ex
+++ b/apps/block_scout_web/lib/block_scout_web/controllers/chain_controller.ex
@@ -2,10 +2,10 @@ defmodule BlockScoutWeb.ChainController do
   use BlockScoutWeb, :controller
 
   alias BlockScoutWeb.ChainView
-  alias Explorer.{Chain, PagingOptions}
+  alias Explorer.{Chain, PagingOptions, Repo}
   alias Explorer.Chain.{Address, Block, Transaction}
-  alias Explorer.Chain.Transaction.History.TransactionStats
   alias Explorer.Chain.Supply.RSK
+  alias Explorer.Chain.Transaction.History.TransactionStats
   alias Explorer.Counters.AverageBlockTime
   alias Explorer.ExchangeRates.Token
   alias Explorer.Market
@@ -15,7 +15,6 @@ defmodule BlockScoutWeb.ChainController do
     transaction_estimated_count = Chain.transaction_estimated_count()
     block_count = Chain.block_estimated_count()
 
-
     market_cap_calculation =
       case Application.get_env(:explorer, :supply) do
         RSK ->
@@ -29,8 +28,18 @@ defmodule BlockScoutWeb.ChainController do
 
     transaction_stats = get_transaction_stats()
 
-    chart_data_paths = %{market: market_history_chart_path(conn, :show),
-                        transaction: transaction_history_chart_path(conn, :show)}
+    # Hack for render during testing
+    transaction_stats =
+    if length(transaction_stats) == 0 do
+       [%{number_of_transactions: 0}]
+    else
+      transaction_stats
+    end
+
+    chart_data_paths = %{
+      market: market_history_chart_path(conn, :show),
+      transaction: transaction_history_chart_path(conn, :show)
+    }
 
     chart_config = Application.get_env(:block_scout_web, :chart_config, %{})
 
@@ -51,14 +60,14 @@ defmodule BlockScoutWeb.ChainController do
     )
   end
 
-  def get_transaction_stats() do
+  def get_transaction_stats do
     stats_scale = date_range(1)
     TransactionStats.by_date_range(stats_scale.earliest, stats_scale.latest)
   end
 
   def date_range(num_days) do
     today = Date.utc_today()
-    x_days_back = Date.add(today, -1*(num_days-1))
+    x_days_back = Date.add(today, -1 * (num_days - 1))
     %{earliest: x_days_back, latest: today}
   end
 
@@ -75,8 +84,6 @@ defmodule BlockScoutWeb.ChainController do
     end
   end
 
-  def search(conn, _), do: not_found(conn)
-
   def token_autocomplete(conn, %{"q" => term}) when is_binary(term) do
     if term == "" do
       json(conn, "{}")
@@ -97,15 +104,9 @@ defmodule BlockScoutWeb.ChainController do
   def chain_blocks(conn, _params) do
     if ajax?(conn) do
       blocks =
-        [
-          paging_options: %PagingOptions{page_size: 4},
-          necessity_by_association: %{
-            [miner: :names] => :optional,
-            :transactions => :optional,
-            :rewards => :optional
-          }
-        ]
+        [paging_options: %PagingOptions{page_size: 4}]
         |> Chain.list_blocks()
+        |> Repo.preload([[miner: :names], :transactions, :rewards])
         |> Enum.map(fn block ->
           %{
             chain_block_html:
diff --git a/apps/block_scout_web/lib/block_scout_web/notifier.ex b/apps/block_scout_web/lib/block_scout_web/notifier.ex
index 40ce428144..194bf67198 100644
--- a/apps/block_scout_web/lib/block_scout_web/notifier.ex
+++ b/apps/block_scout_web/lib/block_scout_web/notifier.ex
@@ -122,11 +122,14 @@ defmodule BlockScoutWeb.Notifier do
 
   def handle_event({:chain_event, :transaction_stats}) do
     today = Date.utc_today()
-    [{:history_size, history_size}]  = Application.get_env(:block_scout_web, BlockScoutWeb.Chain.TransactionHistoryChartController, 30)
+
+    [{:history_size, history_size}] =
+      Application.get_env(:block_scout_web, BlockScoutWeb.Chain.TransactionHistoryChartController, 30)
 
     x_days_back = Date.add(today, -1 * history_size)
-    stats = TransactionStats.by_date_range(x_days_back, today)
-      |> Enum.map(fn item -> Map.drop(item, [:__meta__]) end)
+
+    date_range =  TransactionStats.by_date_range(x_days_back, today)
+    stats = Enum.map(date_range, fn item -> Map.drop(item, [:__meta__]) end)
 
     Endpoint.broadcast("transactions:stats", "update", %{stats: stats})
   end
diff --git a/apps/block_scout_web/lib/block_scout_web/templates/chain/show.html.eex b/apps/block_scout_web/lib/block_scout_web/templates/chain/show.html.eex
index 48dda23aaa..d5f0fcab0f 100644
--- a/apps/block_scout_web/lib/block_scout_web/templates/chain/show.html.eex
+++ b/apps/block_scout_web/lib/block_scout_web/templates/chain/show.html.eex
@@ -5,7 +5,7 @@
       <div class="dashboard-banner-network-graph">
         <!-- Graph -->
         <div class="dashboard-banner-chart">
-          <div hidden data-chart-loading-message class="tile tile-muted text-center mt-5">
+          <div data-chart-loading-message class="tile tile-muted text-center mt-5">
             <span class="loading-spinner-small mr-2">
               <span class="loading-spinner-block-1"></span>
               <span class="loading-spinner-block-2"></span>
@@ -71,7 +71,7 @@
                 <span class="dashboard-banner-chart-legend-label">
                     <%= gettext "Tx/day" %>
                 </span>
-                <span class="dashboard-banner-chart-legend-value" data-selector="">
+                <span class="dashboard-banner-chart-legend-value" data-selector="numTransactions">
                     <%= Enum.at(@transaction_stats, 0).number_of_transactions %>
                 </span>
             </div>
@@ -135,8 +135,8 @@
             <%= gettext "Something went wrong, click to reload." %>
           </span>
         </button>
-        <div hidden data-selector="loading-message" class="tile tile-muted text-center mt-3 w-100" >
-          <span  class="loading-spinner-small mr-2">
+        <div data-selector="loading-message" class="tile tile-muted text-center mt-3 w-100">
+          <span class="loading-spinner-small mr-2">
             <span class="loading-spinner-block-1"></span>
             <span class="loading-spinner-block-2"></span>
           </span>
@@ -161,8 +161,12 @@
             <%= gettext "Something went wrong, click to retry." %>
           </span>
         </button>
-        <div hidden data-selector="loading-message">
-          <%= render BlockScoutWeb.CommonComponentsView, "_tile-loader.html" %>
+        <div data-selector="loading-message" class="tile tile-muted text-center mt-3">
+          <span class="loading-spinner-small mr-2">
+            <span class="loading-spinner-block-1"></span>
+            <span class="loading-spinner-block-2"></span>
+          </span>
+          <%= gettext("Loading...") %>
         </div>
       </span>
     </div>
diff --git a/apps/explorer/lib/explorer/chain/transaction/history/historian.ex b/apps/explorer/lib/explorer/chain/transaction/history/historian.ex
index 474f6fd391..696ba9ff1a 100644
--- a/apps/explorer/lib/explorer/chain/transaction/history/historian.ex
+++ b/apps/explorer/lib/explorer/chain/transaction/history/historian.ex
@@ -1,44 +1,49 @@
 defmodule Explorer.Chain.Transaction.History.Historian do
+  @moduledoc """
+  Implements behaviour Historian which will compile TransactionStats from Block/Transaction data and then save the TransactionStats into the database for later retrevial.
+  """
   use Explorer.History.Historian
+
+  alias Explorer.Chain.{Block, Transaction}
+  alias Explorer.Chain.Events.Publisher
+  alias Explorer.Chain.Transaction.History.TransactionStats
   alias Explorer.History.Process, as: HistoryProcess
   alias Explorer.Repo
-  alias Explorer.Chain.Block
-  alias Explorer.Chain.Transaction.History.TransactionStats
-  alias Explorer.Chain.Events.Publisher
 
   import Ecto.Query, only: [from: 2]
 
-  alias Explorer.Chain.Transaction
 
   @behaviour Historian
 
   @impl Historian
   def compile_records(num_days, records \\ []) do
-
     if num_days == 0 do
-      #base case
+      # base case
       {:ok, records}
     else
-      day_to_fetch = Date.add(date_today(), -1*(num_days-1))
+      day_to_fetch = Date.add(date_today(), -1 * (num_days - 1))
 
       earliest = datetime(day_to_fetch, ~T[00:00:00])
       latest = datetime(day_to_fetch, ~T[23:59:59])
 
-      query = from(
-        block in Block,
-        where: (block.timestamp >= ^earliest and block.timestamp <= ^latest),
-        join: transaction in Transaction,
-        on: block.hash == transaction.block_hash)
+      query =
+        from(block in Block,
+          where: block.timestamp >= ^earliest and block.timestamp <= ^latest,
+          join: transaction in Transaction,
+          on: block.hash == transaction.block_hash
+        )
 
-      num_transactions = Repo.aggregate query, :count, :hash
-      records = [%{date: day_to_fetch, number_of_transactions: num_transactions} | records ]
-      compile_records(num_days-1, records)
+      num_transactions = Repo.aggregate(query, :count, :hash)
+      records = [%{date: day_to_fetch, number_of_transactions: num_transactions} | records]
+      compile_records(num_days - 1, records)
     end
   end
 
   @impl Historian
   def save_records(records) do
-    {num_inserted, _} = Repo.insert_all(TransactionStats, records, on_conflict: :replace_all_except_primary_key, conflict_target: [:date])
+    {num_inserted, _} =
+      Repo.insert_all(TransactionStats, records, on_conflict: :replace_all_except_primary_key, conflict_target: [:date])
+
     Publisher.broadcast(:transaction_stats)
     num_inserted
   end
@@ -49,7 +54,7 @@ defmodule Explorer.Chain.Transaction.History.Historian do
     DateTime.from_naive!(naive_dt, "Etc/UTC")
   end
 
-  defp date_today() do
+  defp date_today do
     HistoryProcess.config_or_default(:utc_today, Date.utc_today(), __MODULE__)
   end
 end
diff --git a/apps/explorer/lib/explorer/chain/transaction/history/transaction_stats.ex b/apps/explorer/lib/explorer/chain/transaction/history/transaction_stats.ex
index e50511646a..4077533976 100644
--- a/apps/explorer/lib/explorer/chain/transaction/history/transaction_stats.ex
+++ b/apps/explorer/lib/explorer/chain/transaction/history/transaction_stats.ex
@@ -9,7 +9,6 @@ defmodule Explorer.Chain.Transaction.History.TransactionStats do
 
   alias Explorer.Repo
 
-
   schema "transaction_stats" do
     field(:date, :date)
     field(:number_of_transactions, :integer)
@@ -28,9 +27,11 @@ defmodule Explorer.Chain.Transaction.History.TransactionStats do
   @spec by_date_range(Date.t(), Date.t()) :: [__MODULE__]
   def by_date_range(earliest, latest) do
     # Create a query
-    query = from stat in __MODULE__,
-              where: (stat.date >= ^earliest and stat.date<=^latest),
-              order_by: [desc: :date]
+    query =
+      from(stat in __MODULE__,
+        where: stat.date >= ^earliest and stat.date <= ^latest,
+        order_by: [desc: :date]
+      )
 
     Repo.all(query)
   end
diff --git a/apps/explorer/lib/explorer/history/historian.ex b/apps/explorer/lib/explorer/history/historian.ex
index 953f9289aa..3fe41702c1 100644
--- a/apps/explorer/lib/explorer/history/historian.ex
+++ b/apps/explorer/lib/explorer/history/historian.ex
@@ -7,8 +7,8 @@ defmodule Explorer.History.Historian do
   Record of historical values for a specific date.
   """
   @type record :: %{
-    date: Date.t()
-  }
+          date: Date.t()
+        }
 
   @doc """
   Compile history for a specified amount of units in the past. Units are defined by historian impl
@@ -25,8 +25,8 @@ defmodule Explorer.History.Historian do
       alias Explorer.History.Historian
 
       def start_link(_) do
-        #Expansion:
-        #HistoryProcess.start_link(Explorer.History.Process, [:ok, __MODULE__], name: __MODULE__)
+        # Expansion:
+        # HistoryProcess.start_link(Explorer.History.Process, [:ok, __MODULE__], name: __MODULE__)
         GenServer.start_link(Explorer.History.Process, [:ok, __MODULE__], name: __MODULE__)
       end
 
diff --git a/apps/explorer/lib/explorer/history/process.ex b/apps/explorer/lib/explorer/history/process.ex
index e3594db61a..dafb8caeb8 100644
--- a/apps/explorer/lib/explorer/history/process.ex
+++ b/apps/explorer/lib/explorer/history/process.ex
@@ -1,5 +1,8 @@
 defmodule Explorer.History.Process do
-
+  @moduledoc """
+  Creates the GenServer process used by a Historian to compile_history and to save_records.
+  Specifically used by Market.History.Historian and Transaction.History.Historian
+  """
   use GenServer
   require Logger
 
@@ -34,6 +37,7 @@ defmodule Explorer.History.Process do
   def handle_info({:DOWN, _, :process, _, _}, state) do
     {:noreply, state}
   end
+
   # Actions
 
   @spec successful_compilation(Historian.record(), module()) :: any()
@@ -42,9 +46,9 @@ defmodule Explorer.History.Process do
     schedule_next_compilation()
   end
 
-  defp schedule_next_compilation() do
+  defp schedule_next_compilation do
     delay = config_or_default(:history_fetch_interval, :timer.minutes(60))
-    Process.send_after(self(), {:compile_historical_records, 1,}, delay)
+    Process.send_after(self(), {:compile_historical_records, 1}, delay)
   end
 
   @spec failed_compilation(non_neg_integer(), module(), non_neg_integer()) :: any()
diff --git a/apps/explorer/lib/explorer/market/history/historian.ex b/apps/explorer/lib/explorer/market/history/historian.ex
index f6d9593cf8..2c6c1d7d83 100644
--- a/apps/explorer/lib/explorer/market/history/historian.ex
+++ b/apps/explorer/lib/explorer/market/history/historian.ex
@@ -1,4 +1,7 @@
 defmodule Explorer.Market.History.Historian do
+  @moduledoc """
+  Implements behaviour Historian for Market History. Compiles market history from a source and then saves it into the database.
+  """
   use Explorer.History.Historian
   alias Explorer.History.Process, as: HistoryProcess
   alias Explorer.Market
@@ -7,11 +10,12 @@ defmodule Explorer.Market.History.Historian do
 
   @impl Historian
   def compile_records(previous_days) do
-    source = HistoryProcess.config_or_default(
-      :source,
-      Explorer.Market.History.Source.CryptoCompare,
-      Explorer.Market.History.Historian
-    )
+    source =
+      HistoryProcess.config_or_default(
+        :source,
+        Explorer.Market.History.Source.CryptoCompare,
+        Explorer.Market.History.Historian
+      )
 
     source.fetch_history(previous_days)
   end
diff --git a/apps/explorer/test/explorer/chain/transaction/history/historian_test.exs b/apps/explorer/test/explorer/chain/transaction/history/historian_test.exs
index 603d0142ca..8f9d8261ed 100644
--- a/apps/explorer/test/explorer/chain/transaction/history/historian_test.exs
+++ b/apps/explorer/test/explorer/chain/transaction/history/historian_test.exs
@@ -6,29 +6,25 @@ defmodule Explorer.Chain.Transaction.History.HistorianTest do
 
   import Ecto.Query, only: [from: 2]
 
-
-
   setup do
     Application.put_env(:explorer, Historian, utc_today: ~D[1970-01-04])
     :ok
   end
 
   defp days_to_secs(days) do
-    60*60*24*days
+    60 * 60 * 24 * days
   end
 
   describe "compile_records/1" do
-
     test "fetches transactions from blocks mined in the past num_days" do
-
       blocks = [
-        #1970-01-03 00:00:60
+        # 1970-01-03 00:00:60
         insert(:block, timestamp: DateTime.from_unix!(days_to_secs(2) + 60)),
 
-        #1970-01-03 04:00:00
-        insert(:block, timestamp: DateTime.from_unix!(days_to_secs(2) + (4*60*60))),
+        # 1970-01-03 04:00:00
+        insert(:block, timestamp: DateTime.from_unix!(days_to_secs(2) + 4 * 60 * 60)),
 
-        #1970-01-02 00:00:00
+        # 1970-01-02 00:00:00
         insert(:block, timestamp: DateTime.from_unix!(days_to_secs(1)))
       ]
 
@@ -39,22 +35,23 @@ defmodule Explorer.Chain.Transaction.History.HistorianTest do
       expected = [
         %{date: ~D[1970-01-04], number_of_transactions: 0}
       ]
-      assert {:ok, ^expected} = Historian.compile_records 1
 
+      assert {:ok, ^expected} = Historian.compile_records(1)
 
       expected = [
         %{date: ~D[1970-01-04], number_of_transactions: 0},
-        %{date: ~D[1970-01-03], number_of_transactions: 2},
+        %{date: ~D[1970-01-03], number_of_transactions: 2}
       ]
-      assert {:ok, ^expected} = Historian.compile_records 2
 
+      assert {:ok, ^expected} = Historian.compile_records(2)
 
       expected = [
         %{date: ~D[1970-01-04], number_of_transactions: 0},
         %{date: ~D[1970-01-03], number_of_transactions: 2},
         %{date: ~D[1970-01-02], number_of_transactions: 1}
       ]
-      assert {:ok, ^expected} = Historian.compile_records 3
+
+      assert {:ok, ^expected} = Historian.compile_records(3)
     end
   end
 
@@ -73,10 +70,11 @@ defmodule Explorer.Chain.Transaction.History.HistorianTest do
 
       Historian.save_records(single_record)
 
-      query = from(
-        stats in TransactionStats,
-        select: %{date: stats.date, number_of_transactions: stats.number_of_transactions},
-        order_by: [desc: stats.date])
+      query =
+        from(stats in TransactionStats,
+          select: %{date: stats.date, number_of_transactions: stats.number_of_transactions},
+          order_by: [desc: stats.date]
+        )
 
       results = Repo.all(query)
 
diff --git a/apps/explorer/test/explorer/chain/transaction/history/transaction_stats_test.exs b/apps/explorer/test/explorer/chain/transaction/history/transaction_stats_test.exs
index b30143a450..72401440fd 100644
--- a/apps/explorer/test/explorer/chain/transaction/history/transaction_stats_test.exs
+++ b/apps/explorer/test/explorer/chain/transaction/history/transaction_stats_test.exs
@@ -5,10 +5,11 @@ defmodule Explorer.Chain.Transaction.History.TransactionStatsTest do
   alias Explorer.Repo
 
   test "by_date_range()" do
-
-    some_transaction_stats = [%{date: ~D[2019-07-09], number_of_transactions: 10},
-                              %{date: ~D[2019-07-08], number_of_transactions: 20},
-                              %{date: ~D[2019-07-07], number_of_transactions: 30}]
+    some_transaction_stats = [
+      %{date: ~D[2019-07-09], number_of_transactions: 10},
+      %{date: ~D[2019-07-08], number_of_transactions: 20},
+      %{date: ~D[2019-07-07], number_of_transactions: 30}
+    ]
 
     Repo.insert_all(TransactionStats, some_transaction_stats)
 
@@ -22,7 +23,6 @@ defmodule Explorer.Chain.Transaction.History.TransactionStatsTest do
     assert ~D[2019-07-07] = Enum.at(all3, 2).date
     assert 30 == Enum.at(all3, 2).number_of_transactions
 
-
     just2 = TransactionStats.by_date_range(~D[2019-07-08], ~D[2019-07-09])
     assert 2 == length(just2)
     assert ~D[2019-07-08] = Enum.at(just2, 1).date
diff --git a/apps/explorer/test/explorer/history/process_test.exs b/apps/explorer/test/explorer/history/process_test.exs
index 4f037150ac..fca1b483f6 100644
--- a/apps/explorer/test/explorer/history/process_test.exs
+++ b/apps/explorer/test/explorer/history/process_test.exs
@@ -13,6 +13,7 @@ defmodule Explorer.History.ProcessTest do
 
   test "handle_info with `{:compile_historical_records, days}`" do
     records = [%{date: ~D[2018-04-01], closing_price: Decimal.new(10), opening_price: Decimal.new(5)}]
+
     TestHistorian
     |> expect(:compile_records, fn 1 -> {:ok, records} end)
     |> expect(:save_records, fn _ -> :ok end)
@@ -43,7 +44,7 @@ defmodule Explorer.History.ProcessTest do
     assert {:noreply, state} == HistoryProcess.handle_info({nil, {1, 0, {:ok, [record]}}}, state)
 
     # Message isn't sent before interval is up
-    refute_receive {:compile_historical_records, 1}, history_fetch_interval-1
+    refute_receive {:compile_historical_records, 1}, history_fetch_interval - 1
 
     # Now message is sent
     assert_receive {:compile_historical_records, 1}
@@ -54,10 +55,9 @@ defmodule Explorer.History.ProcessTest do
     |> expect(:compile_records, fn 1 -> :error end)
     |> expect(:save_records, fn _ -> :ok end)
 
-    #Process will restart, so this is needed
+    # Process will restart, so this is needed
     set_mox_global()
 
-
     state = %{historian: TestHistorian}
 
     # base_backoff should be short enough that it doesn't slow down testing...
@@ -69,7 +69,7 @@ defmodule Explorer.History.ProcessTest do
     assert {:noreply, state} == HistoryProcess.handle_info({nil, {1, 0, :error}}, state)
 
     # Message isn't sent before interval is up
-    refute_receive {_ref, {1, 1, :error}}, base_backoff-1
+    refute_receive {_ref, {1, 1, :error}}, base_backoff - 1
 
     # Now message is sent
     assert_receive {_ref, {1, 1, :error}}