Coral Trend Indicator: A Six Stage T3 Filter, Not an EMA

Written by Dominic Walsh · Published 6 Aug 2026 · Last updated 21 Sep 2026

The coral trend indicator is a T3 filter, not a moving average with a colour on it. Price passes through six identical single pole stages, and the last four get recombined with a fixed polynomial. Coral rising and Coral falling colour the result, with flip markers at each turn.

This build ships as a compiled .ex4 for MT4 and .ex5 for MT5; the screenshots below come from EURUSD H1.

Platforms	MT4 (.ex4) + MT5 (.ex5)
Chart window	Main price chart
Plots	4: Coral rising, Coral falling, Coral flip up, Coral flip down
Alerts	popup, push notification, email, sound
Inputs	33

On the chart: plots and colours

Coral rising carries the line while it climbs against the previous bar.

The falling state hands the line to Coral falling instead.

Coral flip up marks the bar where the state changes upward.

A Coral flip down marker records the opposite turn.

Text and label objects tag recent flips when InpShowTags stays on.

• Coral rising: line, turquoise, width 3
• Coral falling: line, coral, width 3
• Coral flip up: arrow, spring green, width 2, arrow code 233
• Coral flip down: arrow, crimson, width 2, arrow code 234

The method

Six single pole stages

InpSmoothing converts into a smoothing constant, and each of the six stages applies that same constant to the output of the stage before it.

Stage one smooths price, stage two smooths stage one, and so on down the cascade. Six passes is what gives the filter its characteristic shape.

Recombining with the constant

Stages three through six get combined using a fixed polynomial in InpConstantD. The coefficients come from the published set and are implemented as written rather than approximated.

That recombination is the whole trick. It subtracts some of the lag the six stages introduced, which is why the result reacts faster than six plain averages would.

The colour state

Direction comes from comparing the value against the previous bar, with InpFlatPoints available as a dead band for markets that jitter.

Only the buffer matching the current state receives a value, so the line appears to change colour exactly where the state turns.

Reading it correctly

Colour is the state and a flip marker is the change.

This tracks price more closely than a plain average of the same length, because the recombination removes part of the cascade lag.

InpConstantD controls how aggressive that removal is, so it changes the character of the line rather than just its speed.

Six stages need history, so the left edge of a fresh chart carries nothing useful.

Alert channels in this build: popup, push notification, email and sound, one message per closed bar.

Alerts cover popup, push, email and sound on each flip. A bar time check keeps it to one alert per closed bar.

Every Coral Trend Indicator input

Core settings

Setting	What it does	Default
InpSmoothing	Smoothing period sm (published default 21). InpSmoothing sets the period every stage of the cascade uses. It defaults to 21.	21
InpConstantD	Constant d (0.0 – 1.0, published default 0.4). InpConstantD is the constant in the recombination polynomial, on a scale from 0 to 1. It defaults to 0.4, and raising it makes the line more responsive and more prone to overshoot.	0.4
InpAppliedPr	Price: 0=close 1=open 2=high 3=low 4=median 5=typical 6=weighted. InpAppliedPr picks the price the cascade runs on, 0 by default for the close.	0
InpFlatPoints	Slope dead band (points per bar, 0 = published behaviour). InpFlatPoints is a dead band on the direction test, 0.0 by default so any change counts.	0.0
InpTagBars	Draw text tags over the last N bars. InpTagBars is how far back flip tags get written, 300 bars by default.	300
InpTagGapPx	Caption gap from the arrow, in PIXELS.	38
InpMaxTags	Hard cap on captions drawn at once.	12
InpPriceScalePx	Right margin owned by the price scale, in pixels.	62
InpOneClickWpx	Width of the one-click trade panel zone, top-left.	260
InpOneClickHpx	Height of the one-click trade panel zone, top-left.	100
InpX	Panel X offset (px).	14
InpY	Panel Y offset (px) – clears one-click panel.	120

Display settings

Setting	What it does	Default
InpShowArrows	Show trend-flip arrows. InpShowArrows draws the flip markers and defaults to true.	on
InpArrowPad	Arrow distance from the bar (points). InpArrowPad is the cosmetic gap between a flip marker and its candle, 30 points by default.	30
InpShowTags	Show BUY / SELL text next to the arrows.	on
InpBuyColor	BUY tag colour.	spring green
InpSellColor	SELL tag colour.	crimson
InpCapFontSize	Caption font size.	9
InpLabelEdgePadPx	Padding kept clear at the chart edges, in pixels.	10
InpAvoidPanel	Keep arrows and captions clear of the info panel.	on
InpShowPanel	Show the Coral readout panel.	on
InpCorner	Panel corner (0=UL 1=UR 2=LL 3=LR).	0
InpFontSize	Panel font size.	9
InpFont	Panel font.	Consolas
InpPanelBg	Panel background.	RGB 8,26,26
InpBorderColor	Panel border.	teal
InpTextColor	Panel text.	gainsboro

Alert settings

Setting	What it does	Default
EnableAlerts	Master alert switch.	on
EnablePopup	Popup alert.	on
EnablePushNotify	Push notification to the mobile terminal.	off
EnableEmail	Email alert.	off
EnableSound	Play a sound file.	off
SoundFile	Sound file name.	alert.wav

Chart and timeframe notes

The screenshot uses EURUSD H1. A 21 bar cascade on H1 gives a line that holds its state through ordinary pullbacks. On H4 and daily the flips become rare and each one covers a lot of ground. Below M15 the responsiveness that makes this filter attractive turns into frequent state changes.

Where it disappoints

Removing lag also amplifies overshoot. At a high InpConstantD the line can extend past a turn before settling back.

The direction test compares two bars with no threshold unless you set InpFlatPoints, so a one point change flips the state.

Six stages plus the recombination means a long warm up, and the earliest values on a fresh chart are unreliable.

A smoother line still lags. Faster than six plain averages is not the same as leading price.

Copy the compiled Coral Trend Indicator file into your MQL4/Indicators folder, and the MT5 build into MQL5/Indicators, then restart the terminal and drag it onto a chart. The step-by-step guide with screenshots is at how to install MT4 and MT5 indicators.

Related on forexmt4systems.com: Ichimoku Trend Strategy.

Download the Coral Trend Indicator for MT4 and MT5

The zip holds the compiled Coral Trend Indicator build for MT4 and MT5, plus a short README. Compiled files only, no source. Enter your email below and the download link arrives in your inbox.

FAQ

Is the coral trend line just a triple EMA?

No. A triple EMA is three passes; this is six identical single pole stages, and the last four get recombined with a fixed polynomial in InpConstantD. That recombination step is what separates a T3 filter from any stack of plain averages, and it changes both the shape and the lag.

What does InpConstantD 0.4 actually control?

How much of the cascade lag the recombination subtracts back out. Near zero the result behaves much like the plain six stage cascade, slow and smooth. Raising it towards one makes the line far more responsive and more likely to overshoot a turn before settling.

When should I set InpFlatPoints above 0.0?

On a market that jitters enough to flip the state on meaningless changes. The direction test compares the current value against the previous bar with no threshold by default, so a single point of movement counts. A small dead band filters those out.

Why does Coral rising need so much history before it appears?

Every stage of the cascade feeds the next, so stage six cannot produce a trustworthy value until all the earlier stages have settled. With InpSmoothing at 21 across six stages, that takes a considerable stretch of bars before the line means anything.

Are results guaranteed?

No. Trading involves risk. Results are not guaranteed; past performance is not indicative of future results. Use the Coral Trend Indicator as one input. Always backtest before trading live.