A few years ago I posted a link to a study done that demonstrated corals are more resiliant when raised in an environment that had varying temperature.
The takeaway from the study was that corals need to be raised in varying conditions from the start if they are to survive varying conditions in the future.
Established corals raised in tight parameters did not survive when subjected to the new varying conditions.

One of the consequenses of aquarists trying to maintain long term success with corals by maintaining rock steady lighting, water chemistry and temperature is that when corals raised in a steady environment are subject to changes in those parameters, the corals are not strong enough to survive those changes.

In nature, corals are subject to environmental changes including lighting, salinity and temperature.
Our commitment to keeping corals within tight parameters produces fragile corals.

The best you can do for your corals is learn what conditions they were kept in previously and don't let your tank conditions wander too far from those conditions.
It's neither easy nor simple to do.

Here's a link to the study:
http://onlinelibrary.wiley.com/doi/1...199.x/abstract

The title of the study is "Effect of fluctuating thermal regime on adult and larval reef corals" Putnam 2010 Invertebrate Biology


And a free article from Dr. Shimek on the subject:
http://www.ronshimek.com/salinity_temperature.html

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I've definitely noticed this over the years. My old 90-gallon reef with halides over it used to fluctuate from 79-80F at night to 84-85F during the day. It did great. Would it have done better if I tightened up that temperature swing and kept the peak lower? Probably. However, the corals were very resilient. :D

I think this also true of other parameter swings too, such as KH.

It's frustrating when you check all parameters which check out fine, but your corals are still dying.
I think reviewing the past conditions that the corals have been exposed to is more important than what the current conditions are.

Sometimes of course, changes are too great for even strong corals to withstand.
Think of what's currently happening to the Great Barrier Reef.

Good info. Thank you

Thing is, I haven't really changed the parameters too much. They went up slightly but that was over the course of weeks so it shouldn't have bothers them right? Only real drastic change was the t5 to led but that shouldn't kill every coral in the tank.

I'm still thinking it's the sand bed that's releasing hydrogen sulfide because of the smell. I decided to remove half of my sand bed last night and the water and smell was disgusting. I'll post a pic later for you guys. I'm mixing more water right now to remove the rest of it.

Not the best move to remove your sand bed when the tank is recovering from a crash, next time have your water ready so you can do a large wc at the same time, people usually skim the top layer when removing their sand bed 1/2" at a time...

I don't have much else to lose l'm down to a few spa frags now lol. I syphoned out my sand while I did a 50 gallon water change. Matched all parameters in the tank before I did the change.

I checked it out this morning and everything looked ok. First morning I didn't find anything dead. Fingers crossed!

Your corals look to be a large size, so maybe think of what conditions they were kept before this new tank setup.
H2S can be removed from the water with activated carbon or by oxidizing with ozone. Hach makes a kit for measuring H2S, but it's best of course to reduce sediment buildup in the first place.
H2S is deadly to aquatic animals as much as carbon monoxide is deadly to humans. It doesn't take much to be fatal.
Good luck!

When you do your WC, do you typically siphon the sand bed on a regular basis? Maybe I missed it but how often and how much of a WC do you do?

Good luck. You're probably right that you don't have much to lose at this point. Hopefully the removal will help turn things round for you.

I wouldn't do it that way. Exposing deeper layers is the opposite of what you want to do. When I remove a sand bed I remove the entire depth of sand from say 1/4 of the tank, then replace that area with new sand, then next week remove the next 1/4 and replace, and so on.

I do 2-3 water changes per year and each one about 150 gallons. I do syphon the sand to get rid of any detritus in there. My last water change was October but I dose cal alk mag and trace elements. Then a big water change to "rebalnce" the trace elements.

I did another water change this morning and ended up siphoning out the rest of the sand. I checked up on the tank a couple hours ago and everything looks good. The trumpet corals were more open and overall the Lps looked happier.

Maybe this is a sign that your current approach is not working. Lots of people do these minimal or zero water change methods successfully. You may be missing some key point. Have you thought of doing a Triton test when you're some months into no WC? Which salt mix do you use?

Maybe a triton test might be a good idea. I didn't even think about that. I'm going to see if removing the sand helps, if not I guess my next step would be a triton test.

When I initially setup the tank I used h2oceans and then over the summer I switched to aquaforest.

This morning the tank looks stable again. No new die off and the water is incredibly clear. It's had a little bit of cloudy water for a few months. I just couldn't get it this clear even with all the filtration and filter socks, there was always a slight cloudiness to the water.

Is there somewhere who does the triton test within Canada?


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One of the LFS sells the kits so I'd imagine he has some method of getting them sent In.

How much are they? I have been curious about doing it


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I have no idea at all but it's a pretty cool method of testing.

If you want more info, his website is https://www.marineexperience.ca his name is Neil.

Most LFS have the packs you can buy for sampling which gives you a sample number and labels then you send them to an address in the USA. It's about $60 for the sampling pack, then postage to USA. You get your results online in about 3 weeks.

Hey fellows it's been a week now since I took out my sandbed and everything looks stable again. I Haven't had any losses since then or tissue loss and the corals are opening up nicely again and coraline algae has been growing quite a bit. Some of my corals which I thought were dead are actually showing little bits of colour on some branches as well so I might be able to save them.

I can't really pin point the loss on anything other than my sandbed. The water was quite dirty in the bin that I siphoned all the sand and detritus into but I dont think it could have been the detritus traped in the sandbed that caused this because my ammonia nitrites nitrates phosphates alays came up as 0.

All i can think of is if the power heads were blowing the sand around which caused hydrogen sulfide to slowly release into the water? I think carbon neutralizes the hydrogen sulfide but maybe it was a steady slow release? I'm stumped...

This barebottom thing takes some getting used to but I think it's growing on me :mrgreen:

Thank you everyone for your help!

Glad to hear things are improving.
One thing to keep in mind, depending on how old your live rock is, it could be contributing an extra amount to your detritus buildup through a process called bacterial turgor.
Basically, turgor is when the pressure builds up in bacterial cell walls and forces waste products out.
The bacteria in the top few millimeters of your live rock could just be cleaning out the old live rock.