Corals suddenly not looking great

[ReefSlice]

I had a nutrient problem recently in my 40g and have been doing large weekly water changes (20-30%) to fix that problem, as well as dosing nopox (although only 2 ml/day for 50g system). I finally got my nitrates below 5 and everything looked great for a few weeks and I even saw growth like I've never seen in the tank. And then it seemed to stall and SPS have shown less PE as well as LPS not opening up nearly as much. I also had one new frag STN over a few days. Parameters are pretty good, no3 3-4, po4 0.00 (hanna low range, getting ULR in a few days), calcium 430, mag 1400, kh 9.6. Only things I can think of is that either my reef needs some phosphate, or when I switched from red sea coral pro to blue bucket a month ago, and my kh fell from 11 to 9.6 over 3 weeks (figured with my now lower nutrients I wanted to slowly lower kh), my corals did not adjust well. I'm leaning more towards having no phosphate, as my tank has no algae, even the glass rarely gets enough algae to wipe clean, and the corals seem to be dull, almost like they're starving. In order to try and increase nutrients, I have dropped my nopox dose down to 1 ml/day and increased feeding to 2x a day, however there's only so much LRS I can feed to just 2 clownfish. Even when I register .02 po4, usually it's back down to .00 in a day or two. My skimmer stopped producing chunky skimmate and just coats the neck with it now and gets light tea colored skimmate in the cup. Anyone have any idea what to do to get coral back on track and growing? Should I dose phosphate or perhaps try some reefroids or acro power?

 

[Lasse]

The combination of low PO4 (0) and high alkalinity (9.6) has been reported to cause events like this.

Sincerely Lasse

 

[Randy Holmes-Farley Verified Community Expert]

I had a nutrient problem recently in my 40g and have been doing large weekly water changes (20-30%) to fix that problem, as well as dosing nopox (although only 2 ml/day for 50g system). I finally got my nitrates below 5 and everything looked great for a few weeks and I even saw growth like I've never seen in the tank. And then it seemed to stall and SPS have shown less PE as well as LPS not opening up nearly as much. I also had one new frag STN over a few days. Parameters are pretty good, no3 3-4, po4 0.00 (hanna low range, getting ULR in a few days), calcium 430, mag 1400, kh 9.6. Only things I can think of is that either my reef needs some phosphate, or when I switched from red sea coral pro to blue bucket a month ago, and my kh fell from 11 to 9.6 over 3 weeks (figured with my now lower nutrients I wanted to slowly lower kh), my corals did not adjust well. I'm leaning more towards having no phosphate, as my tank has no algae, even the glass rarely gets enough algae to wipe clean, and the corals seem to be dull, almost like they're starving. In order to try and increase nutrients, I have dropped my nopox dose down to 1 ml/day and increased feeding to 2x a day, however there's only so much LRS I can feed to just 2 clownfish. Even when I register .02 po4, usually it's back down to .00 in a day or two. My skimmer stopped producing chunky skimmate and just coats the neck with it now and gets light tea colored skimmate in the cup. Anyone have any idea what to do to get coral back on track and growing? Should I dose phosphate or perhaps try some reefroids or acro power?

I agree that low phosphate is a reasonable possibility. Food doesn't need to be eaten by the fish, but it might become unattractive and dosing phosphate is simple and easy to try (and to stop if needed).

 

[ReefSlice]

Should I continue to perform water changes to drop alk or should I focus on getting more nutrients into the tank? Doing the water changes in turn drops my nutrients even more, but not sure if the alk has anything to do with my problem at the moment. Also, I have 9 sps frags and 3 lps and they use hardly any alk, which is why I've been using water changes to drop the alk, as otherwise it does not get absorbed by corals very quickly at all. Maybe .2 kh/week, is this normal?

 

[Randy Holmes-Farley Verified Community Expert]

Water changes are unlikely to reduce alkalinity unless you start with a low alk mix. What salt are you using?

 

[ReefSlice]

I switched from red Sea coral pro to blue bucket about a month ago, and since then I've done 3 water changes 5-10 gal, bringing kh down from 11 to the 9.6 it's at now. The original plan was to bring it down to around 8 over a few weeks to match up my nutrients with the right alk, however my tank has become incredibly clean in this time (easy with a barebottom to suck up all detritus every water change), and these coral problems have arisen, causing me to rethink the weekly water changes. I also doubt it but could that 1.4 dkh swing over 3 weeks cause this? My symptoms to me sound like a starving coral, but what do I know, I'm no sps expert.