Crushed coral to raise KH?

[newyorkmfk]

I’m looking to raise the KH in my ray tanks... my KH in both tanks is like zero and I always have a slight bit of ammonia and nitrite because of it... how much crushed coral is recommended to add? One tank is 500 gal and the other is 350 gal. I know that raising the KH will also raise the ph but I don’t want the ph to go up drastically.

 

[joe jaskot]

Add some baking soda to increase your kh.

 

[TwoHedWlf]

How much depends on how finely it's crushed, where it's put, etc. But assuming you're putting it a canister filter and it's about pea size, I'd say start with filling a whole tray in the filter and then keep an eye on the PH and KH for a few weeks then go from there. In my 120g tank I have a whole tray of my FX-5 filled with coral fingers.

 

[spotfin]

What is the pH of your tank now

 

[newyorkmfk]

What is the pH of your tank now

Normally I kept it at 6.5. But I’ve been raising it to raise the KH. Currently 7-7.2

 

[duanes]

Here is a fluidized bed reactor I built to keep buffering capacity up, in about 300 to 500 gallons of tanks.
It is about 4 ft high, and 8 " in diameter, and holds about 4-5lbs of fine aragonite sand (crushed coral) and a little over 10 gallons of water.
Although it only raised pH a couple tenths, the alkalinity would be about 60ppm without it, but running bring alkalinity to 90-100ppm.
As the aragonite would dissipate I needed to add a little at a time, every few weeks.
At first I built it with a top (pressurized, but opted for an open top, for easier maintenance, and it really didn't need pressurization to work. The weight of the unit filled, was almost 90 lbs.
I also used a check valve to prevent back siphon of the fine sand during power outages.


As you can see by the fry tank in the background, right after adding new aragonite, the water would get slightly milky looking

 

[RD.]

In my area crushed oyster shell (chicken grit) is FAR less expensive than crushed coral, and works just as good or better according to some papers that I read in the past. If you have a farm supply store in the area you can usually buy a 25-50 lb bag for relatively cheap. Just make sure to rinse well before using.

 

[Coryloach]

Generally, crushed coral hardly makes any difference. It is very difficult to dissolve.

The options are soda bicarbonate - but that would build up sodium if water changes are not up to scratch.

Alternative is, using Potassium Hydrogen Carbonate (KHCO3 ) which would be specifically beneficial if the tank is planted as it would add potassium, an essential for plants macro nutrient. It maybe more difficult to source than soda bicarbonate.