Seachem Denitrate: The Best Way to Make It Work

Seachem Denitrate – and Seachem Matrix – can do a fantastic job of helping to lower the nitrates in your aquarium. But there is one very simple, yet important step you must take in order to unlock their full potential.

It took me 6 months to figure this out. And once I did, the impact it had on lowering my nitrates was incredible.

Seachem Denitrate

First, let me point out that Seachem Denitrate and Seachem Matrix are both the same exact media. The only difference is the size of the pieces. Denitrate pieces are about the size of a pea. And Matrix pieces are about the size of a cherry.

The secret to making them work is placing them in the right amount of flow.

The instructions for Denitrate say it should be placed in flow that does not exceed 50 gallons per hour. And the instructions for Matrix do not say anything about flow. (They do hint that it is meant to be used cannister or drip filters, but that’s it.)

Having heard on some forums that Matrix is supposed to be better for lower flow applications, I put some in a media bag and dropped it into my sump.

Over 6 months it hadn’t lowered my nitrates one bit.

So, I did a little more digging and came across a thread on the Seachem support forums that changed everything. It contained a comment from a Seachem rep that said the ideal flow for Denitrate is 20 – 50 gph. And the ideal flow for Matrix is anything over 20 gph.

After spending 6 months in low flow in my sump, my Matrix was covered in crud. I could’ve rinsed it off and re-used. But, being lazy, I decided to just spend $10 on a new bottle of Denitrate instead. (I went with Denitrate because I figured the smaller pieces would provide more surface area for the nitrate-eating bacteria to grow on without taking up any additional space.)

This time though, I put it in a DYI nitrate reactor to make sure it got at least 20 gph of flow (35 gph to be exact).

What a difference!

Within 2 weeks my nitrates fell from 16 ppm to 2 ppm – and have remained there ever since.

It was so amazing and so simple. For more than 8 months I could never get my nitrates to stay below 12 ppm (they usually hovered around 16 ppm). Then, the simple change of giving the Denitrate media a bit more flow completely solved the problem.

And the best part is, it never needs to be replaced. Simply give it a good rinse every couple of months to remove any detritus that gets stuck on its surface and it will work forever.

So that is the key to getting fantastic results with Seachem Denitrate or Matrix: a minimum flow of 20 gph.

Oh, and if you use Denitrate, also be sure the flow does not exceed 50 gph. Otherwise, the water will pass through the media too quickly and the anaerobic bacteria living in its micro-pores will not have time to consume the nitrates.