sea hare, DSB, and anoxic zone

[astroboy]

I'e had some long term troubles with hair algae, probably feeding off live rock that I had in another tank, and set dry for a couple of years and which I never cleaned off, since my water parameters are good. I run GFO, chaeto in the sump, new bulbs, nitrates and phosphates read zero. Of course, that might be because the hair algae grabs them up, but I have only one fish so I feed very little. I use a good RO/DI setup for water, been using Instant Ocean for this tank, which has been set up for seven months. The salinity is usually a bit low about 33ppm. I'll be upping that to 35 with a massive water changed this weekend. I'm not sure if slightly low salinity might be a problem for sea hares. Alkalinity is usually about 5-6 dkh, I have trouble keeping it where I'd like it to be. pH ranges from 8.3 during the day to perhaps 8.0 or 7.9 at night. 

 

I figure my best chance is to get a sea hare to eat all the hair algae so that the waste products can be removed by skimming and an experimental remote DSB (uses rock wool, got the design from a guy who breeds freshwater angels. His water has 10ppm NO3 out of the well, has N03= 2ppm once its gone through the DSB. There's a PhD dissertation on this. But that's a topic for another pose). But the sea hares keep dying after a few days, even with the acclimation times running from one to six hours. 

 

The tank has 2-2.5 inches of fine grained aragonite (more or less mud) on the bottom, and I do see some dark zones against the glass which I'm told are anoxic, and generally contain hydrogen sulfide.

 

I'm wondering if the sea hairs are burrowing into these pockets and getting poisoned. They live long enough to make it back to the surface if that's what's happening. Corals don't appear to be stressed at all. 

 

I"m going to do a 90% water change this weekend (I've done this before, successfully). I'm wondering if it would be a good idea to take a few powerheads and really stir up the sand bed as I'm siphoning the water out, and also siphon out enough sand so that I have maybe an inch on the bottom, little enough that no anoxic zones can form. I would have thought that wouldn't happen with a two inch sand bed, but there you go. My question is, are these hydrogen sulfide pockets likely to be a problem?

 

Do anyone have advice on what eats hair algae? I'm running a Grey Seas skimmer rated for a 300 gallon tank on my 90 and it's great at sucking bad stuff out, so I think once the algae is eaten it will be history. 

 

Thanks

 

 

 

[zygote2k]

Only a 90g tank with one fish?

Too easy.

1) Catch fish and save 25-50% of clear water.

2) Take rock out and scrub all of the HA off with a brush and rinse in remainder of tank water.

3) Take out half of the sandbed.

4) Refill, throw fish in, place rock accordingly.

5) Sit down, drink beer and appreciate your sparkly clean tank.

[Jim Mc]

I had a similar problem and I isn't over yet but I have definitely turned the corner and it is almost gone.  I should say upfront that all things being equal I would follow zygote2k advice.  I have sort of an experiment going so keep in mind what I am typing is not proven to work.  With that said here is what is helping combat HA breakout.  Also I have one arm at the moment so this is a bit of a forced experiment.

 

You have to get it short first not much eats it long.

 

Pull it out with your fingers so you get the big stuff.  I use a toothbrush occasionally.

 

Sea Urchins seem to do a decent job when its shorter but they don't particularly target HA for feeding it is more happenstance.  I use tuxedo and pincushion.

Turbo Snails again when it is short.  It seems like most herbivores will eat it when it is not in outbreak.

Look to increase your detritus eating cuc.  I use tiger tail cucumbers, nassarius snails,  bumblebee snails, and I have chocolate chip stars in the sump and fuge (not in the DT).

 

My purple tang, 2 bar rabbit, and lawnmower blenny don't seem to touch it.

 

Started a bacteria dosing regimen. I used zeobak and zeozym.  Daily for about 2 weeks then began following the normal dosing.

 

That seems to have it turning around for me, but again I think water changes and the rest of the previous post will help faster.

[taiscici]

Magnificent fox face is awesome with long hair algae, also Mexican turbo snails are good too.

[Jason Rhoads]

 

The tank has 2-2.5 inches of fine grained aragonite (more or less mud) on the bottom, and I do see some dark zones against the glass which I'm told are anoxic, and generally contain hydrogen sulfide.

 

If that is all the deeper your sand bed is, then what you are seeing is likely algae growing against the glass due to the refracted light.  

[OcalaReefGirl]

+1 on the fox face