Hmmm, a conundrum...

[MGR201]

So I've recently experienced a bit of a problem in my BioCube 29 and I thought I'd toss it to the community for commentary/advice. In the last month I've noticed that my colony of Blue Anthelia (which formerly was almost impossible to kill and had started spreading like a weed throughout the tank) had started to decline. The mat that had grown on the back wall of my tank shrank and disappeared and many of the polyps appeared to shrivel and die off. Everything else in the tank appeared robust, including my LPS-- favia and hammer corals, GBTN and other soft corals and zoanthids. Recently, however, I have had a string of Astrea snail losses (four in the last month). At first I thought it was just the blue legged hermit crabs killing them for their shells but I think they were merely being opportunistic and feasting on already dying creatures. My parameters are as follows:

Temp: 78
Salinity: 1.027
pH: 8.2
Ammonia: 0
Nitrite: 0
Nitrate: 5.0ppm
Ca: 520 (could this be too high for the softies? The Favia look great)
Mg: 1470
Alk: (here's another problem perhaps? Salifert test comes back 2.63 me/l while Red Sea comes in low, about 1.6 me/l)

Here's a picture of the declining colony:

 

[MGR201]

Oh yes and Phosphate reads negligible using Salifert and 0-0.1 using Red Sea.

 

[tosiek]

Your Calcium is way high it should be at 430, your mag is also way high it should be around 1300, and your salinity is also high and that should be around 1.023-1.024. Your nitrates should be lower than that. A 5 reading is extremely high and I would check if you timed the test right.

With the calc and mag readings where they are I would expect your alk to be low. You need to balance out your mag because 1500 is what people run when trying to get rid of bryopsis and +1500 usually causes alot of death and destruction with certain coral.

I dunno if your kits are bad but you apparently have a problem if your seeing these things happen in your tank.

By the way, its not a surefire thing that because one coral is doing fine that the tank water is fine and it must be something else. Some coral adjust better than others.

Also, I might replicate your tank parameters because my tank is being overrun with the blue cloves. sigh.

 

[prattreef]

If your salinity is high, all the other levels will be high as well (denser solution) and that makes your Alk. reading actually lower and more of a concern. I disagree that 5ppm nitrate is very high or even concerning. I'd do a dilution to get the salinity down a bit and then re-test. If the Alk. is still low (I'm assuming you use 2-part) just add part 1 for a few days until the Alk. comes up ( at the same time this will force the Ca. down ) and once you reach the right balance, resume adding both parts.

Of course, this might not help the problem, but it is the 1st thing I'd look at.

 

[MGR201]

Well, I guess the best advice is that "the solution to pollution is dilution" so I will do a few water changes over the next week and bring the salinity down along with Ca & Mg. Hopefully, Alk will rise with a little "one part" effort over the week and the colony will reignite its former blistering growth. Thanks for the suggestions!

 

[tosiek]

You can just grab a sample batch of your water and add a bit of RO to it to lower the salinity and retest. Doing water changes will cause the rest of your parameters to balance out to what the mixed saltwater parameters are so you won't know what the problem was now =0)