I need help, badly. Please...

[Kahuna]

I am having huge issues with my tank, and especially my SPS corals. Death, and not STN or RTN, but just sudden dead patches. Mostly acros and montis are affected. Scroll, pagoda, some certain acros, and LPS are OK. This started 9 days ago.

Please, read what I have, what I've done, and then give me your best ideas.

I have a 90g reef tank setup with the following features:

90g display tank, 30g sump with fuge.

ATI 8 X 39w dimmable Sunpower fixture with the following light cycle:
Set it up for CH1 (Fiji Purple and Blue Plus) to come on at noon, 50% at 1300, 65% at 1400, 65% at 1900, 50% at 2000, off at 2130.
CH2 ( 3 Blue Plus and 3 Coral Blue) to come on at 1300, 50% at 1400, 65% at 1500, 65% at 1800, 50% at 1900, off at 2030.
This was an ALL LED tank until two months ago and still my corals did not thrive and would sporadically die off, but not like this.

Two Ecotech MP40s running lagoon at night, reef crest during the day, and 1 hr in the morning and at night running nutrient export mode. Max speed is set to 75%. A lot of flow.

The tank is about 60% ceramic EcoRoche rock, and 40% live rock, about 40 lbs total.

The sump has 4 filter socks that are changed every 4 days and washed on sanitary cycle with a teaspoon of bleach, extra rinse, and then air dried

I have a Reef Octopus Diablo 160 skimmer. I don't get much skimmate - ever, no matter how I set it. Bubbles are great.

I run a kalkwasser topoff and a calcium reactor.

I run GAC and GFO reactors.

My sand bed is about 1" deep and is siphoned off during each water change

Temp = 79°F
DkH = 9-10.5
Ca = 450ppm
Mg = 1300ppm
Nitrates are testing over 50ppm
Nitrites = 0
Phospates = 0.03ppm
No copper

RO/DI water in use - TDS = 0

I was gone after a big dieoff for about 8 weeks. During this time no water changes were done, my wife has advanced MS and could only keep up the top-off RO water. When I returned, the tank actually looked pretty good.

I did an immediate 30% water change and a full cleanup of everything.
I returned to my 25% water change every two weeks.

I am now set up after some DIY work to do a 40% water change every day if I want and no more 5 gallon buckets. Yay.

I think the nitrates are killing my tank. I went to carbon dosing with BioBacter7 and biopellets in a reactor this week.

Am considering a 40% water change 2-3 times a week to get the nitrates down.

Please give me your best advice or thoughts. There are no pests and nothing is eating or attacking the SPS's. This is husbandry and chemistry, but I'm out of ideas.

TIA

Kev

 

[dunk373]

I sure we all want to know what test kits your are using, salt type, salinity etc.

 

[Kahuna]

I sure we all want to know what test kits your are using, salt type, salinity etc.

Sure, no problem.

Salt is Red Sea Coral Pro, tried some Seachem but didn't like the way it didn't mix well. Salinity is 1.025 using a calibrated refractometer. Salinity verified against a friend's refractometer.

Test kits -
Red Sea Pro Reef Foundation for alk, ca, and mg
Red Sea Pro Algae Control for nitrate and phosphate
Red Sea Pro Marine for N02, N03, pH, and alk backcheck.

Was using Salifert, ran these kits against the Salifert before I switched over, I like these because I can just buy the reagent refills and are every bit as accurate as the Salifert.

BTW, other than what's mentioned in the first post, I dose 5 ml of reef iodide per month to help my crabs and shrimps molt.

We feed rinsed brine shrimp, and quality flake in moderation every other day, and feed algae daily for the 3 tangs.

The cleanup crew is small to keep the bioload down. We have:

1 very large ORA derasa clam - 10-12"
1 large ORA blue spotted squamosa clam, 8-10"
1 4" melinarus wrasse
1 aussie blonde naso tang - 4"
1 Red Sea desdjardini sailfin tang - 3.5"
1 yellow eye kole tang - 3"
1 male and two female red spotfin anthias - 2" each
2 Marshall Islands true percula clowns, 2" each
1 bluespot goby, 3"
1 shrimp goby and pistol shrimp

4 mexican turbos, 2 scarlet hermits (small), about 8 nasarrius snails, and about 20 very small Hawaiian cleaner snails (1/4" long each), 3 emerald crabs, 1 sea cucumber - not the atomic bomb type that tends to nuke the tank, 2 large pink serpent stars, 1 3 year old blue linkia star.

 

[dunk373]

everything seems very good except of course the nitrates. Maybe the wc you did on your return gave a shock to the corals? I have not used pellets but hear they take a while to setup and get going so give them time. I would continue on the water changes. Just keep an eye on the corals if they get better or worse. I know nitrates are bad and this comment may be off base but I don't think a 50 nitrate will kill the sps in spots. Is it possible something touched the coral and caused the dying spots? maybe a spike in alk?

 

[Kahuna]

We had a low dip in alk about 10 days ago (6.2dKH) for about a day or so because I did;t know the Apex went out and was not dosing. Had to replace the Apex.

 

[MammothReefer]

ALK swing could be the culprit.

 

[NeilFox]

ALK swing could be the culprit.

Agreed. I had a similiar issue with alk. It had dropped to around 6 ish. What made the problem worse was trying to raise it too quickly. I boosted it up to seven in one day then 8 the next. By most accounts this should be safe but I don't agree. From now on I only raise alk 1/2 degree DKH in a day if I need to move it. I never go above 8.4 DKH. My tank is pretty new but when some of my SPS went into growth mode I wasn't paying attention and they were using up more Ca and Alk than I thought they were. I also had the same tissue loss you are talking about.

 

[BrentH]

Alk swing I think also .... I know it's prob safe but the bleaching of filter pads has always made me netvous

 

[danil]

If SPS are not doing well first thing to look into - alkalinity. If you had confirmed Alk swing - that's your problem. SPS are unforgiving for Alk drops. Keep it stable and watch the corals if STN will worsen clip effected branches off.
GL