Maintaining kH and pH

[OgreMkV]

My tank has a problem maintaining pH and hardness. I end up using adding a buffer solution about once a week (one dose). That brings the hardness right up (which pisses off the torch coral) and keeps the pH about 8 - 8.5.

Is this fairly normal or do I have some kind of issue?

 

[TropicalNorth]

I assume when you're talking about hardness you are talking about alkalinity (KH).
Corals and coralline algae deplete the alkalinity constantly. Alkalinity is calcium and they are using it to make their skeletons.

So to maintain the alkalinity you have to add something. I use Bicarbonate of Soda 'cause it is really cheap, doesn't have any impurities and buffers the ph to a maximum of 8 (so you can add a fair amount without messing with the ph).

I probably add about 1/2 to 3/4 of a teaspoon every 2 days on a 20g just to keep the KH stable. I do have a fair few corals though.

The pH however should stay pretty stable even if the KH goes up and down a bit. If the KH is really low though it will cause the pH to go down. The other main reason for a low pH is low oxygenation either through not enough aeration or because the tank has a tight fitting lid on it.

 

[OgreMkV]

My tank does have a relatively tight fitting lid, but there are several openings and a HOB filter... I haven't done an oxygen test, but it should be fine. I have no fish, one quarter sized crab, 3 small mushrooms, a torch coral, and some start polyps (about 15 square centimeters worth). That's it. O2 shouldn't be any issue.

The torch and shrooms are growing, but my calcium level is fairly constant at about 600.

It's the carbonates that are falling rapidly and the pH.

 

[DoctaQ]

thats a fairly common problem because for every 2.8(?) dkh of alk that get used only 50ppm of calc gets used up
at 600 ppm of calc you will use up 12 dkh of alk before you really need to dose ca again, coraline will also use up calcium and alkalinity.
when you dose an alk supplement you should dose it slowly and only a little at a time because it spikes your ph which is probably why your torch gets all sad

 

[fsn77]

Our reef tank requires daily alkalinity buffer additions to maintain the alkalinity levels. Having an auto top-off greatly simplifies this for me, as the reservoir is filled with RO/DI water with Seachem Reef Builder mixed into it. Since the auto top-off pumps small amounts of water into the tank many times each day, it helps to avoid large swings in KH.