I lowered my DKH with Acid. Now what?

[RussC]

Okay, still working on lowering my DKH after an overdose. Down from 12.6. But I think I've bottomed out using water changes because my new water has a DKH about 11.4. So I made 10 gallons of new water and used acid to reduce the DKH to 8.3. Now what?

1) I'm running an air stone to remove the CO2. How long do I do this?
2) Will a 10 gallon water change even make an impact on my system? I was a little gun-shy using acid for the first time with this, so didn't really feel like doing my normal 20 gallons. Don't want to make too big a swing too fast.
3) Even if I do a 20 gallon change, is there any way to tell how much I need to lower the DKH in the new water in order to make an overall impact on my tank? How much is too much?

 

[Fishfinder]

If you have salt that mixes to 11dkh I would keep my tank at 11dkh or get different salt. Lowering you tank to 8 and then using 11dkh salt isn't typically going to keep things steady

 

[Fishfinder]

What is your target alk?

 

[Reeferdood]

How do the corals look?
Before you go dumping acid perhaps just let it come down on its own?
Big swings are really hard on sensitive livestock.
Good luck..

 

[Randy Holmes-Farley Verified Community Expert]

How do the corals look?
Before you go dumping acid perhaps just let it come down on its own?
Big swings are really hard on sensitive livestock.
Good luck..

He added acid to the salt mix, not the tank.

 

[Reeferdood]

Copy that,
sometimes reading forums with the phone is harder to read....

 

[Randy Holmes-Farley Verified Community Expert]

Okay, still working on lowering my DKH after an overdose. Down from 12.6. But I think I've bottomed out using water changes because my new water has a DKH about 11.4. So I made 10 gallons of new water and used acid to reduce the DKH to 8.3. Now what?

1) I'm running an air stone to remove the CO2. How long do I do this?
2) Will a 10 gallon water change even make an impact on my system? I was a little gun-shy using acid for the first time with this, so didn't really feel like doing my normal 20 gallons. Don't want to make too big a swing too fast.
3) Even if I do a 20 gallon change, is there any way to tell how much I need to lower the DKH in the new water in order to make an overall impact on my tank? How much is too much?

1. Can you measure pH? That will tell you.

2 and 3. The alk after a water change is the weighted average of the two starting alks.

Tank at 12 dKH, 20% change with 8 dKH --> 0.8 x 12 dKH + 0.2 x 8 dKH --> 9.6 + 1.6 dKh = 11.2 dKH

You can drop the alk of the new water to 1 dKH if you want.