No nitrates: marinepure vs skimmer part time

[superdragon]

Hi, my sps when bought look good and usually after about 3-4 months they grow and encrust a little bit then become pale and start to bleach. I've eliminated potential pests, and though pale are still alive with PE, some don't make it after 3-5 months. So far I can only isolate it to having no nitrates.

Alk is about 8.3
Salinity is 1.026
Cal is 425
Mag over 1300
Nitrate 0.0

Lately, I added 2 big blocks of marinepure 8x4 to my sump on February (thought I had a water quality issue). I also have a oversized skimmer SRO 6000sss for my 120g with a neck cleaner. I think either... the blocks are way too efficient or the skimmer or both.

I have upped by feedings to 3x a day, throw in occasional frozen food, and coral frenzy daily, run the skimmer dry and still can't get nitrates up.

Should I pull the 2x marinepure blocks or run my skimmer at night/part time? Consider dosing nitrate?

thanks for any input

 

[kevlow]

My system has trouble maintaining detectable nitrates as well. SPS fade and lose PE. The LPS pieces will stop growing and start to STN.

For many years I thought having undetectable nitrates and phosphates was good, so I fed sparingly and owned oversize skimmers.

Now I overfeed the fish , set the skimmer for twelve hours a day, feed a little coral food twice a week, and still need to dose some nitrate. I try to maintain 'trates at 5-10 while phosphates around .02-.04. The corals have never looked better.

 

[PedroMurcia]

Ever happened to me that, you can remove the skimmer cup a few days to help those blocks is that they work very well.

 

[moatdaddy]

i ran into the marinepure block nitrate issue. phosphates not so much, i control them with phosgaurd. I added more fish and coloration returned, my nitrates are 0 and phosphates are still 0. Yet i know that since my coloration returned and some algae is growing that the corals have enough to eat to keep it at 0.