The Puffer Forum

Can I use just gravel as a substrate in a brackish aquarium < 0.010

You mean 1.010? Crushed coral or aragonite sand is recommended to keep the pH steady, around 8.

Pufferpunk wrote:You mean 1.010? Crushed coral or aragonite sand is recommended to keep the pH steady, around 8.

Yea I was half asleep when i posted this (just did a 16 hour shift)....hm...sounds good.

I use crushed coral and sand in my brackish tank. Crushed coral might help but make sure you use marine salt as that will be the most effective way of bringing up the PH.

There's no real advantage to using crushed coral or coral sand in a brackish water aquarium *unless* you are using an undergravel filter.

The buffering effect of old, algae- and bacteria-covered coral sand just sitting at the bottom of the tank is minimal. Partly it is because the water isn't in contact with much water, and partly because the coral sand is insulated from the water by the coating of micro-organisms.

You get a much more effective buffering system by stocking a canister or wet/dry filter with crushed coral (or some equivalent calcareous chemical filter medium). This frees up your aquarium to be decorated with something more attractive and in keeping with the aquascaping. Laterite-enriched gravel if you're growing plants for example, or beach sand if you're keeping gobies and flounders.

Cheers, Neale

I'd have thought weekly vacuuming created a grinding action on CC in a brackish tank and would mix in enough powdered and ground up crushed coral to make a half decent buffer if water flow was generally good near the surface of the substrate. I agree in undisturbed-substrate marine settings it would seem to do little after a few week-months of gathering slime and bacteria... but the stuff grinds HARD on itself whenever I vaccum it in my GFs tank, and it seems like it creates lots of new surface and fresh fine particles to dissolve.