How can I lower my alkalinity?

[slingfox]

If you go the muratic acid route be careful when handling it and wear safety gear (gloves + eye protection). It is readily available at the local hardware store since it is used to clean concrete (+other household uses) as well as the pool supply store since it is used to chemical balance swimming pools.

 

[EricR]

For lowering alkalinity, I mix new saltwater with Sodium Bisulfate (direct from Loudwolf website) to make low alkalinity (<0.1 dKH) new water, then do small water changes with that.

Randy has a thread on Sodium Bisulfate here:
Sodium Bisulfate to Reduce Alkalinity

For quick estimates of alk effect per water change schedule over time, I like this calculator:
Water Change Calculator

 

[michealprater]

Bring your salinity up to 35 and it will correct. Numbers aren’t far off… looks solid.

 

[MnFish1]

Try measuring the alk in your new salt water. If it reads normal and resuming water changes with it does not keep the alk in check, you can lower the alk further in the new salt water with muriatic acid or sodium bisulfate.

Doesn't pure RODI water have an alkalinity of 0? Do you think this could be a bad batch of salt - or a poorly mixed (dry) salt?

 

[Randy Holmes-Farley Verified Community Expert]

Doesn't pure RODI water have an alkalinity of 0? Do you think this could be a bad batch of salt - or a poorly mixed (dry) salt?

It should, yes. Poor mixing of an inhomogeneous batch is more likely than an actual bad batch, and test error is not unlikely too.

 

[Randy Holmes-Farley Verified Community Expert]

Bring your salinity up to 35 and it will correct. Numbers aren’t far off… looks solid.

High alk won't correct by raising salinity.

 

[Viking_Reefing]

???? Need some help

Calm down. Just let it go down on its own. Unless the high alk is due to a ton alk being added at once there’s no reason to panic here.

 

[MnFish1]

It should, yes. Poor mixing of an inhomogeneous batch is more likely than an actual bad batch, and test error is not unlikely too.

How much could high nitrate play a role in high alkalinity?

 

[michealprater]

High alk won't correct by raising salinity.

Is 12 dkh all that bad though? I regularily run mine between 11 and 12. I have to dose the hell out of calcium, but the corals seem to grow like crazy.

 

[Miami Reef]

Is 12 dkh all that bad though? I regularily run mine between 11 and 12. I have to dose the hell out of calcium, but the corals seem to grow like crazy.

Exactly. High alk is great for coral growth.

I run 10-11dKH.

Maybe some people don’t want fast stony coral growth, especially if their tank is grown out or if they want to keep low nutrient tanks. I think high alkalinity is feared by many reefers.

 

[MnFish1]

Exactly. High alk is great for coral growth.

I run 10-11dKH.

Maybe some people don’t want fast stony coral growth, especially if their tank is grown out or if they want to keep low nutrient tanks. I think high alkalinity is feared by many reefers.

I have seen problems with high alkalinity, high light and low flow with SPS - IF not adjusted slowly. I'm not sure it hurts at 12.4, but - it can make it difficult to add new corals, etc - if, for example your LFS uses an alkalinity of 8. But generally, my experience meshes with yours

 

[michealprater]

Even my zoas and bubble tip nems seem to love it!

 

[Miami Reef]

I have seen problems with high alkalinity, high light and low flow with SPS

I agree. That’s a very bad combo for SPS. Dana Riddle observed similar effects:

 

[Alex_hairymoney]

Bring your salinity up to 35 and it will correct. Numbers aren’t far off… looks solid.

My salinity is actually high, the apex salinty probe isn’t i use it for average but as it sits my salinty is @ 1.027

 

[Randy Holmes-Farley Verified Community Expert]

How much could high nitrate play a role in high alkalinity?

High nitrate would not cause high alk. As that nitrate accumulates, it reduces alk along the way.

if nitrate is high and then drops by consumption, that produces alk.

 

[Randy Holmes-Farley Verified Community Expert]

Is 12 dkh all that bad though? I regularily run mine between 11 and 12. I have to dose the hell out of calcium, but the corals seem to grow like crazy.

i didn't say it was good or bad. Just advising on how to change it if that's what the OP wants.

 

[MnFish1]

High nitrate would not cause high alk. As that nitrate accumulates, it reduces alk along the way.

if nitrate is high and then drops by consumption, that produces alk.

Yes - thats what I meant - as nitrate falls alkalinity increases. So if one had a high nitrate, and for example bacteria started processing it (with tank maturity?) or some other method, the alkalinity will rise - how often do we see this in a home aquarium. I remember a thread similar to this one a while back.

 

[Miami Reef]

Yes - thats what I meant - as nitrate falls alkalinity increases. So if one had a high nitrate, and for example bacteria started processing it (with tank maturity?) or some other method, the alkalinity will rise - how often do we see this in a home aquarium. I remember a thread similar to this one a while back.

For every 50ppm of nitrates depleted, you will add 2.3dKH of alkalinity.