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pH stabilizing ie opposite lighting in a refugium


Pygmy Octopus
Apr 28, 2007
I was wondering if anyone found that there cuttles were sensitive to the drops in pH that are experienced during the night. The reason I ask is that I'd like to set up some type of refugium but since I'm going to go with a smaller tank without a sump I'm either going with a HOB or a intank refugium to house some chaeto. The advantage to the HOB is that I can alternate the light cycle versus main tank to limit the pH shift, but the in-tank would be a less expensive option.

Any opinions?

Hi Flampton,

Why not put the chaetomorpha in the cuttle tank? That way the cuttles will get the benefit of having somewhere to hang out and you can see how they blend in with a different background.

I used to have caulerpa with my Sepia officinalis.

Will it be S bandensis that you are keeping?

What is your main reason for the refugium? You might find that the cuttle tank itself becomes like a refugium because of all the mess from the cuttles the amphipods, copepods and worms will breed rapidly in the tank anyway.

If it is to stabalise pH then what sort of a drop are you getting, as long as its not dropping below 8 it will be fine. Do you buffer your aquarium?

Hi Colin,

I currently don't have a setup, Its in the planning process right now. As for the buffering do you mean like the sand and its CaCO3? Or something else?
Yeah, the sand is a good start but with water used which is very soft like my tap water or RO water the buffering capacity of the sand and salt doesn't last long.

I normally have to use extra in the form of a pH and KH buffer such as otherwise the pH is unstable.

In a cuttle tank I prefer the substrate to be made up of mainly silica sand and a scattering of aragonite. Corals sand/gravel could be a bit rough on their skin if burying in, especially when young.

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