Sudden 'brown film/slime' algae bloom

[apurintun]

I have a one-year old reef (my third over ~15 years): 60 gal tank, extremely low and stable bio load (no fish, 30-50 astraea/cerith snails and 20-25 red-reef hermits, and just a handful of mushrooms, polyps, leather-type corals).

I had near-zero nuisance algae until all of a sudden about 5 weeks ago I started noticing brown film/slime on the front glass (which previously I almost never had to clean), then on the rocks, and eventually the substrate (gravel). Now it grows at a rate that I need to clean the rocks with a toothbrush every 3 or 4 days. Not good.

Checking things over I discovered: 1) a jammed pump had reduced total flow by ~30% or so; 2) my light bulbs (220 watts of compact fluorescents) are about 1 year old; 3) my RO/DI prefilters are also about 1 year old.

The only other change to the system is that I started using 'Chemi Pure Elite' approximately 2-3 months before the problems started (prior to that I was not using any chemical filtration); I changed the Chemi Pure after about 3 months, so it is not particularly 'old'.

I have consistently changed about 7% of the water every week; occasionally a larger amount (12-15%).

In the past several weeks I have replaced the lights and fixed the pump. For good measure I also threw in another pump so now total flow is ~25% greater than before the problems started. More recently I replaced the RO/DI pre-filters. So far I have NOT discontinued use of Chemi Pure Elite.

My best guess is that the old RO/DI pre-filters were the major culprit, as the problem only seemed to get worse when I did one of my larger water changes around 3 weeks ago (after fixing the pump and changing the lights). I didn't think to test any of the water that these old filters were producing - too late now.

Any advice? Should I step up the water changes (now that I have new pre-filters)? How much should I aim to change and over what period? Is it best to do 2 or 3 BIG changes (15+ gal), or just stick to 6-8 each week? What else? Shoul I ditch the Chemi Pure? Thanks for the advice.

[apurintun]

Something else I forgot: whatever the problem is also seems to be killing my Astraea snails; I would guess half or more of them have died in the last 10-15 days. All were from a 'batch' I procured a year ago. They (or some other snail) were reproducing until just before this problem (handfuls of tiny snails on the glass, probably many more elsewhere (invisible)).

[BigKahuna]

Sounds like Dino's, I hope it's not though. Does the brown slime have air bubbles in it creating floating streamers attached to whatever it grows on and does it recede in the darkness to come back with a vengeance when the lights come back on? The snail carnage sounds like a sure Dino type sign, nothing seems to be able to eat them w/o it being fatal and when they overgrow corals it seems to have pretty nasty affects as well on the livestock.

[apurintun]

I agree this seems like a dino bloom (from what I've read in the past); what to do about it is the question. Any ideas?

[apurintun]

Or even better: what (probably) CAUSED it? AND what to do now???

[BigKahuna]

I think the general consensus is to do a full tank-wrapped-in-a-blanket blackout for 72 hours minimum after siphoning out what you can. I did this and it seems to help quite a bit but the problem with them is they can go from zero to tank wide infestation in a few days the rate they grow with no natural predators eating them. What I did that seemed to finally get rid of them was after a hurricane imposed blackout of over a week that seemed to really hurt them but maybe not eliminate them was to run essentially actincs only for a month. I haven't seen them since. YMMV and I would recommend searching for threads on controlling them. Good look, they can be nasty stuff to deal with.

[apurintun]

Thanks. I see a lot of discussion about the role of pH and/or alkalinity, neither of which was I carefully monitoring (my bad). Darkness, raising the pH and alk, and possibly dosing with hydrogen peroxide (?) or a commercial algicide seem to be recommended... And making sure to have lots of water flow... If anyone can add to this, or provide link(s) to the 'definitive' historical thread(s), I would be obliged.

[apurintun]

Also some discussion of stopping or cutting back on water changes.... counter-intuitive, but recommended more than once,

[AWDcameoLSX]

I'm in the middle of that battle right now any only thing that has helped was blackout 4 days bit it came right back. Next thing that has been slowly working is hydrogen peroxide dosing. Didn't see much for 1ml per 10 gallons once a day but after I bumped it up to that amount twice a day it's making a noticeable difference.