What is up with my phosphates?

[joekidwell]

Hey yall. A couple weeks ago my phosphates bottomed out .00 I skipped my last waterchange and increased feeding to get them to .08 another week goes by and I test them today and are back to .00

Tank is 6 months old and my lps and sps are struggling.

All other parameters are
Nitrate 5
Alk 9.3
Ca 420
Mag 1320

The only thing that gets added to the tank other than food is calk in the ato.

I have 70 gallons total water volume but use a Aquamax DFC 180 skimmer, is this skimmer the culprit?

 

[blaxsun]

What are you using for a testing kit?

 

[joekidwell]

What are you using for a testing kit?

All hannah except for the nitrate and calcium those two are salifert.

 

[joekidwell]

What are you using for a testing kit?

More specifically for the phosphate it's the ulr phosphate.

 

[joekidwell]

I just read an article from reef builders that calcium hydroxide can bind phosphates into the rocks and sand. I'm thinking I should take my kalk offline for a while after reading that.

 

[Randy Holmes-Farley Verified Community Expert]

I just read an article from reef builders that calcium hydroxide can bind phosphates into the rocks and sand. I'm thinking I should take my kalk offline for a while after reading that.

All calcium carbonate surfaces can and do bind phosphate. I would not get caught up in kalkwasser being to blame but higher pH (and alk) in general can help drive that process for a couple of reasons. As an aside, I'd be careful about chemistry advice from most reef blogs. Even when mostly accurate, it is often oversimplified to the point of being incorrect when applied by a reefer to a situation that is not part of the "mostly" accurate description.

Feeding more or dosing phosphate may be needed regardless of the kalkwasser and I'd take that approach now.