Tank problems

[captexas]

Alright, I have a 75g well established tank that has been running for over a year and is fairly stable as I don't do much to it other than maybe a monthly water change. I've been having some problems with my tank lately and I'm not sure what is going on. The problems consist of a few things. I am having to clean the glass daily from algae, some of it being a nasty almost rust colored coating. Some of my corals polyps are not extending as much as they used to and some are not coloring up like they were. Last week I found a dead cleaner shrimp, one that I have had for a year or so. Yesterday I noticed my flameback angel acting strange and today I found it dead, after having it for many months.

The algae on the glass I attributed to depleted filters on my RO/DI unit. The retracted polyps and loss of colors on the corals I throught might be my 10k XM bulbs shifting in color as they have been in use for awhile. Also the water current in the tank has changed as I had to remove one of my Sea Swirls and send it in for repair. I am puzzled about the shrimp and angel fish.

I tested my tank and found nothing to be of concern other than my KH to be at 4.2dKH (Alk 1.49meq/L). PH shows to be 8, calcium at 400ppm, and ammonia, nitrate, and nitrite all show 0. All using Salifert test kits. As some of you know, I was having problems with my calcium reactor. I thought I fixed it, but I guess not as the Alk levels are so low. I went ahead and disconnected it for now and I'm going to slowly add some Kent Superbuffer to try to get the levels up.

Could the low Alk/dkH levels have killed the shrimp and fish? All my other livestock seem ok. I'm a bit frustrated with this tank right now as I hadn't had any problems for so long and now all of this. Anyone have any ideas? Maybe there is something else I am missing.

[Tim Marvin]

I would raise the alk and I'll bet the loss of flow has something to do with it. Did you notice this change within a few days of the seaswirl being removed?

[Tim Marvin]

By the way, shrimp only live a few years anyway, so it could have been it's time.

[captexas]

The junk on the glass has been going on for awhile, but I kind of think that is the top-off water. I really can't say for sure when the corals started acting up, but I would imagine their problems could be attributed to the flow, halides, and the low Alk level although a few of the corals still look fine.

I was wondering about the age thing with the shrimp, but don't know what to think about the angel. I did add a fox face recently and between it and my hippo tang, they could have been picking on it. I didn't find any nip/bite marks on it, but I guess they could have just overstressed it.

[GaryP]

Could the algae on the glass be diatoms? If so, that part of the problem could be from silicates which could be a result of the RO unit.

Also, could the alage be dinoflaggelates? They can be toxic to a grazer like the angel.

[captexas]

Oh, another thing I forgot was that I had a sudden hair algae bloom on 1 zoo frag rock that I got awhile back. I thought that was really strange that it only happened on that rock and nowhere else. Just too many weird things happening at the same time, but probably all related somehow.

[NaCl_H2O]

I doubt the dKH level played any role in the shrimp/fish, but what is your Mg level - that could be keeping your other levels down? If the Angel was acting strangely, then dies, I would think it may have been injured during a boxing match with the tangs? The water flow change may have altered their "territory" and caused some new battles.

On the shrimp, I agree it may have just been it's time. IME an established cleaner is VERY hardy.

I do water changes more often than monthly, and that combined with the potential poor RO/DI quality is probably giving you the environment for the diatom bloom.

FWIW?

[captexas]

Actually, now that I am looking through Gary's handy Nuisance Algae Guide, I think the hair algae was actually Bryopsis which is toxic to herbivores.

[captexas]

Gary - I don't think it was dinoflagellates, might be diatoms. I think the stuff on the zoo rock I had was bryopsis and wonder if that could have caused problems with the angel.

[GaryP]

It can be toxic as well if it grazed on it. Check with Larry. He's the Bryopsis expert.

[captexas]

Alright, now I lost my second cleaner shrimp! I'm getting worried here :(

[NaCl_H2O]

What's your SG and Temp? Are you sure your SG & Temp measuring is correct? I have had Temp and SG swings due to faulty testing! I now have dual thermometers, and two methods for cross checking SG now (Refractometer & floating/bulb hydrometer)

I will never trust one source for temp or SG again!

[captexas]

Temp is ok, I have my chiller on a temp controller which has it's own temp probe and I also keep a glass thermometer in the tank. On the SG, I thought of that tonight. I use a refractometer that I calibrated when I got it like 2 years ago so that could be off. I can't seem to find my cheapy plastic hydrometer to get a basic cross check on it so I'm not sure. I know shrimp are more sensitive to SG changes so I need to check it somehow.

[GaryP]

Are you running carbon in your tank? If not, I would suggest it. There could be some sort of toxic organic compound that is undetectable at fault here. If nothing else, it will eliminate one more possibility.