Raising pH in a marine aquarium has always been a big problem, but now we can use Aquatic Exclusive’s CO2 Scrubber together with AE ScrubX.

One of the biggest problems we have in a marine aquarium, and one that has few solutions, is having a very low pH value. Too low. Having it low for too long could be a problem for coral growth and the well-being of our fish, partly because low pH stimulates excessive algal growth.

We can partially remedy this problem by keeping the KH high, and keeping it constant. Chemically, in fact, KH acts as a buffer for pH, sustaining it when it decreases. This is not a real solution, however, because carbonates in the aquarium are not infinite, and so at some point the KH will drop and no longer work so well. Another solution would be to create a refugium with a reverse photoperiod, but it needs a lot of space to do this for it to be effective, so it is not everyone’s cup of tea.

Do we have any other arrows for our bow? For the past few years it has been seen that a CO2 reactor, a CO2 Scrubber can help us so much. Let’s see how, and let’s look at Aquatic Exclusive‘s proposal.

Our video of CO2 Scrubber from Aquatic Exclusive

Relationship between CO2 and pH

But let’s start with the simple things. How can we find out if we have a pH problem in the aquarium due to having too much CO2 in he house? In a totally empirical way I would suggest that we measure the pH in the aquarium normally, with the windows closed. Then we should open the windows for a day and measure the pH again at the same time as the previous day. If it has risen, it means that we have too much CO2 in the house that spills into the aquarium, lowering the pH.

If you think that this measurement seems too complicated or somewhat impractical, I don’t blame you. But in any case we can see how to employ the CO2 scrubber in the aquarium, because, unfortunately, we have so much CO2 at home.

How a CO2 Scrubber works

The CO2 Scrubber is nothing more than a cylinder, filled with a particular type of resin, connected to our skimmer. Basically, with its use, the skimmer will no longer use the air that is inside the cabinet to create the bubbles. Air that would otherwise have a higher CO2 content which would be transferred into the water. The CO2 would be “amalgamated” in an extremely efficient way, with the aquarium water, resulting in lowering the pH.

Instead, air entering the skimmer will be drawn into the CO2 Scrubber‘s air intakes and passed inside the resins that are responsible for removing CO2 from the air. These resins, in this case the AE ScrubX, are color-changing. They start white and turn fuchsia once they are saturated with CO2.

How is Aquatic Exclusive’s CO2 Scrubber SR500 constructed?

AE’s CO2 reactor is very simple, but very well made and practical. Let’s start with the technical features.

Diameter80 mm
Height170 mm
Free internal volume500 ml
Suitable for aquariums up to400 liters
Price59 dollars

The cylinder uses a red gasket to ensure a seal, as you can see in the following photo. And as I said in the video, colored gaskets always capture me.

Underneath the lid, you can see the 6 holes that provide the air inlet, a flow that can be slowed by a handy locking screw. Used mainly to tune the reactor, and make less noise.

On the base of the reactor, you can see the groove that channels the air, which after passing through the resins, in this case the AE ScrubX, must exit through the small duct that ends on the cap and where the tube that is to be connected to the skimmer is to be engaged.

For attachment to the glass (outside) sump, where there is no other support, there is a small L with a screw to tighten the socket. It screws through a pair of screws to the top circular plate. If you don’t need it, just avoid mounting it.

AE ScrubX resins to absorb CO2

The resin that Aquatic Exclusive offers is its own AE ScrubX, which costs $35 per liter of resins. That is enough for two refills of the SR-500 Scrubber.

In conclusion

Keeping the pH high in the aquarium has always been a pipe dream. Very difficult to do in practice. For the past few years, the possibility of using CO2 Scrubbers, such as the SR-500, has made it possible to sustain pH with little effort. Of course, technically, we don’t raise the pH with this object, but we prevent it from lowering due to the CO2 in the air in our homes. What is amazing is that the SR-500 only costs $59, and with the $35 AE ScrubX resins that guarantee two refills, it can be done in a very simple way.


 Extremely useful in aquarium;
 Well constructed; 
 Moderate size;
 Ridiculous cost and simply monstrous value for money;


 Nothing remarkable;

Aquatic Exclusive CO2 Scrubber SR-500 – summary table

Construction quality

[Translated by Aisja Baglioni]

Disclaimer: Thanks to Aquatic Exclusive for giving us CO2 Scrubber SR-500 and the AE ScrubX resins for this review.

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