Trouble with coral. Possibly related to sand bed?

[djf91]

Hello everyone,

So as of late I’ve been having trouble with some of my corals and any new frags I add to the tank. This started roughly a month ago. Millepora frag started browning and losing almost all polyp extension after having been doing well for a month. My green slimer Acropora frag which had grown about an inch in the past month hasn’t grown now for about a month and has lost most polyp extension, other frags have had their good and bad days. I purchased a birds of paradise birdsnest frag several days ago and it was looking good but now has all of the sudden started to stn from the base.

Tank overview: Has been setup for about 1.5 years. Battled Dino’s for a very long time and lost some coral but also Had some success in first year. Finally beat Dino’s with UV at the end up 2019.

50 gallon cube w/ 20 gallon sump. Skimmer, GFO, Chaeto. 250 watt metal halide. Lots of flow provided by gyre + additional smaller powerheads.

parameters: Alk.: 8.4 Cal.: 400 Phos.: 0.06 nitrate: 2 Mag: 1500

I have tried changing parameters around slowly: lowering and raising phosphates, raising nitrates, etc. Alkalinity has been rock solid.

At this point I am at a loss. I have been wondering about one thing however: roughly about the time everything started going downhill is the same time I added a tiger pistol shrimp for my watchmen goby pair. Well he has certainly gone to work moving around sand under rocks and causing massive detritus storms. Sand bed is 2-3”. Does anybody think this could be it? Could he be releasing something into the water column from this 1.5 year old sand bed?

Thanks for any insight you can provide!

 

[Mikeltee]

250mh over a 50gal? Wow bro... no wonder your stuff is dying. That is an insane amount of light imo.

I have a 30" tall tank and run 150mh. If I run them more than 5hr a day stuff dies. T5s run 12.

 

[djf91]

I think you’re looking at it from the wrong perspective. When assessing light for an aquarium don’t focus on the volume of the tank and wattage but more so how far the corals are placed from the bulb and par. All corals are 12”+ away from the mixture. Additionally, The corals were growing fine, with good polyp extension and color for a month before this all started over night. There are smaller tanks from the past before LEDs that used 250 watt metal halides just fine.

 

[malacoda]

I highly doubt it has anything to do with the sand. Mg looks a little high but not a major suspect either.

If you've just gotten past dinos though, your tank's microbiome may not be back in balance yet. Give it some time.

I had what I would consider a mild case of dinos for ~ 3 months. Coolia mostly. Covered all of the sand and a little bit of the rocks. Not very stringy though. Even with it being a mild case some corals struggled. Some died. (Yet others did fine). Other than bringing my PO4 up to ~0.10 and my NO3 up to ~10 I essentially just let it burn it self out. Even after the last sign of it faded,still took a few weeks for the tank to come back to a healthy balance.

The first sign it had was that tunicates, sponges, amphipods, spaghetti worms, feather dusters began to quickly reappear.

And once they did, the change in vibrancy and behavior was very noticeable across pretty much all of the corals and growth took of like a rocket.

I would just hold your current parameters and trying giving it a few more weeks to balance out on its own.

 

[djf91]

Yes I’ve thought about that too. Things still don’t seem perfect from an algae perspective. The glass grows a brown film every 3 days or so that scrape off. I’m not sure if it’s Dino’s or not but it’s nothing like the brown snot growing on my zoas and lps several months ago.

I can remember at the beginning of this tank and other tanks I’ve had in the past always getting a light green film algae but now currently the film on the glass is a dark brown.

Here are some pictures of one of the corals I mentioned above

March 13th

April 8th

April 24th

 

[djf91]

I’ll add also that things had been steadily improving and looking better for the past 4 days. And then lastnight the pistol shrimp went on a rampage in a whole new area of the sand bed and today everything looks worse.