Help high nitrates and dying corals

[fmuakkassa]

Nitrate levels have been creeping up in my tank and they hit 100 ppm and I start losing some corals. Two disc corals and elegance coral died within days! Bubble corals not opening much. Fish are OK. Also Caulerpa in Miracle Mud refugium are not growing anymore!
My tank is 180g with live rock, miracle mud refugium, and additional sump with Karollin calcium reactor. I use RO water only. All parameters (ph, temp, alk, amonia, nitrite, calcium, magnesium, iodine (0.04 ppm slightly low), phosphate, strontium (slightly low) are normal. Only abnormality is nitrate. Also I started adding iron on daily basis to improve Caulerpa growth. Free iron and chelated iron are still zero and hence I don't think the iron killed my corals.
I admit I am lazy at frequent water cahnges but I did an 18 g change then another 38g in 24 hrs then another 38g in 48 hours and my nitrate are still high (50-75 ppm). I cut down on fish feeding (I might have been over feeding).
Any other ideas or suggestions to keep my nitrate down and get my Caulerpa going. Should I keep adding iron (using a Haggen test kit here otherwise I use Salifert kits).

Thanks

Farid

 

[Boogiechillin]

Have you added any more livestock recently? I can't remember the details, but I seem to recall that you were at about maximum capacity there for a while. I don't suppose anything is missing?

If you're doing sizable water changes, then you probably don't have to worry about dosing iron. Odds are that you might do more damage than good. Your salt mix includes enough iron that you should be ok unless you're growing forests of caulerpa.

Is anything stirring up that mud in the sump? That's the only potentially sticky area I'm seeing in your setup. What kind of substrate do you have in the main tank?

Take a water sample in to a LFS and get that reading corroborated...there's always the chance that the kit itself is bad.

 

[fmuakkassa]

No, I have not added any new fish. I have 13 of them and have been trying to catch the arceye hawk (without success so far) so I can get a clean up crew. No dead fish there. All accounted for.

I am doing sizable water changes now to get my nitrates down (did another 30 g today). I stopped adding iron and iodine for now.

There is nothing stirring the mud in the sump. Just a boat load of copepeds there but nothing bigger. I have a thin layer (1/4 to 1/2 inch) of araginte gravel and some shells in the main tank. I need to add about 50-100 lbs. of live rock more.

I don't know why the Caulerpa stopped growing though.

I tested a concentrated sample of Kent Marine iron solution with the Hagen iron test and it did register high values. I orered a Salifert kit to compare.

Do you think it is time to get a protein skimmer.

I still believe I over fed and introduced too much protein in the system.

Thank for the help, as always.

 

[Boogiechillin]

A protein skimmer would help, and it's always a good thing to have. Do you vacuum through that gravel when you do water changes? Might be some waste accumulating down there.

Is the caulerpa dying or just not growing?

 

[fmuakkassa]

No, I don't vacum the substrate.

The Caulerpa total mass is declining. No mass death there. Few branches showing new growth.

Any suggestion about a decent protein skimmer? Brand, size, plus minus ozoner etc.?

Thanks