Alkalinity still running low, what’s wrong?

[frankiereef]

I’m trying to raise my alk from 7 dKh to 8 using Seachem Reef Builder but I cannot hit the level. My calcium is 420, salinity 1.024, temp 77.5. Any one can help?

 

[chipmunkofdoom2]

How much are you dosing per day?

Also, your salinity is a little low, which means magnesium might also be a little low. Are you testing for Mg? If so, what are the results?

 

[Bulldog39]

I fought with this for weeks then realized my magnesium was like 1300

 

[Syntax1235]

1300 mag is plenty high enough to avoid imbalance issues.

What size tank? Reef builder may be an expensive way of raising alk for a larger tank. Are you dosing alk/ca/mag regularly? If so, how? You may have better success using soda ash and using a calculator to determine amount. Have you double checked the accuracy of your alk test kit?

 

[Graphicsplus]

Are you running a phosphate reactor? I just changed my media and am experiencing a drop in dkh. Apparently a quick drop in phosphate can cause alkalinity drop as well.

 

[Randy Holmes-Farley Verified Community Expert]

Are you running a phosphate reactor? I just changed my media and am experiencing a drop in dkh. Apparently a quick drop in phosphate can cause alkalinity drop as well.

how much did you drop it? which media?

 

[Graphicsplus]

I use Phosban and I noticed a coral that wasn't quite right so I checked dkh and it had dropped down to 6.5 from around 9 in a 2 day period. I needed to reorder the media and while I researched which to get I read that it can lower alkalinity so I'm guessing I may have either used to much in my reactor or put the flow to high but Im glad I caught it soon and am dosing to raise it now.

 

[Randy Holmes-Farley Verified Community Expert]

GFO (like Phosban) can induce precipitation of calcium carbonate on it and downstream of it for a variety of reasons. The iron itself can catalyze precipitation, and having phosphate and organics (GFO binds organics too) reduced in the water can accelerate precipitation.

Changes in phosphate may also alter coral growth and calcification rates, which can, in turn, alter alk levels.