Cichlid Fish Forum banner
1 - 10 of 10 Posts

· Registered
21 Posts
Discussion Starter · #1 ·
Hye everyone!

Just a quick question,

I'm setting up a malawi tank and well i purchased pool filter sand (Silica sand), what i want to to know is

Will the silica sand raise or lower my ph?
Or will my ph stay constant?
Also do you think i need some crushed coral as buffer?
If so what ratio to the silica sand?
And if I need crushed coral to raise the ph can i just mix the crushed coral with the silica sand?

Thanks :)

· Registered
299 Posts
If you're going to be keeping fish that require buffers in the water, the pool filter sand is totally inert so won't change any water parameters.

If you're worried that you may run low on buffers, you can always get some crushed aragonite or coral(aragonite begins buffering at a lower pH than coral, so you'll get harder water), put it in a few old stocking or a media net, then put it in whatever type of filter you use. It works as a biological media and buffers the water. I have it in the filters in both of my rift lake tanks.

· Registered
913 Posts
have you measured the GH and KH as well.

once you know what you water parameters are you can then adjust to bring it to the correct levels.

1ml/10l of sodium bicarbonate will raise the KH by 110ppm (6dKH) or thereabouts
1ml/10l of Epsom salts will raise the GH by 70ppm (4dGH) or thereabouts.

and in case your wondering, Lake Malawi Has a pH of 8.2-8.8 GH of 4-6 and a KH of 6-8.

I get the water out the tap with pH of 7, GH 0.5 KH 0.25 so add 1.5ml/10l of both the Epsom salts and bicarb.

· Registered
13 Posts
Just use baking soda to raise your kH and pH. It will mildly raise the pH.

If baking soda doesn't raise the pH enough, bake it in your oven at 250 - 275F before adding it to your tank.

Baking soda is NaHCO3. It will dissolve as Na+ (sodium) and HCO3-(bicarbonate). This will directly raise your kH and mildly raise your pH.

If you heat it, NaHCO3 becomes Na2CO3. 2NaHCO3 -> Na2CO3 + H2O. Essentially heating baking soda will drive off a molecule of water vapor, turning it into sodium carbonate (washing soda). This will raise your pH a lot at the same time as raising your kH.

If you don't want to bake baking soda to get washing soda, Arm & Hammer has "Super Washing Soda" which is 100% washing soda, no detergents or fragrances. It may not be as high quality as baked baking soda since baking soda is certified food grade. I have not used it so I can't vouch for it.

Calcium carbonate is very slow to dissolve and is kind of poor at setting up a good buffering system if the tank water isn't already balanced. I wouldn't trust crushed coral or holey rock to set up a good buffer system at the right pH.


You can just use something like this: ... uffer.html

It's a blend of carbonate and bicarbonate salts that will set the pH and kH right where you want them.
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.