New to forums, help needed

[dkordella]

How many topic titles come by like that, eh? 

 

I returned the hobby a couple years ago. Back in the 90's I was a lot more involved and had a more ambitious setup that was also largely automated. I was out of the country and an extended power outage wiped out everything and I left the hobby until a couple years ago. 

I set up a modest tank, a 29 gallon that I intend to be a "fish only with live rock" style. At the moment the only critters are a small Percula Clown and a little damsel. There are a small handful of turbo snails. Lighting is a marineland LED "reef" model with the whites on about 8 hours/day.

 

To make a long story short and sweet, I have been continuing to fight a losing battle against cyanobacteria (red-slime) and brown algae (diatoms). I've also got a few patches of thick stands of green hair algae.

 

 

About a month ago I upgraded my skimmer to Reef Octopus BH 100 which I thought should be overkill for a simple 29 gallon tank. It's producing lots of foul-smelling tea-colored water (thicker gunk builds up around the inside lip but doesn't make it into the cup). I do 20% water changes about every other week.

 

I use a 75-gpd RO/DI filter that's a little over a year old (I have neglected to replace the sediment and carbon-block filters, new replacements are now on the way). 

 

When I measure phosphate and nitrate, they are never detectable. My background is in chemistry and ecology, so this reading doesn't surprise me as all the nutrient is obviously rapidly incorporated into biomass. 

 

 

My questions:

 

1. I have a small (less than 2 cm thick) bed of aragonite gravel on the bottom of the tank. Is this simply acting as a nutrient sink? Should I get rid of it? 

 

2. Assuming the replacement cartridges are not enough to reduce the addition of phosphates/silicates, should I consider a phosphate reactor? 

 

3. I'm experimenting with dosing Kalk to precipitate phosphates. Thoughts? Comments?

 

Thanks!

[Origami]

As long as you don't have an ongoing problem with phosphates leeching from the rock - it's possible, in which case an acid wash may be advised - it's more likely that you're overfeeding and there's been an accumulation of organics in the water of which some may skim out and some may not. The algae and the cyano are obviously getting nutrition from some continuing source. Manually export the algae and cyano. Run carbon to see if you can't pick up the organics. One option is to discontinue your water changes and let the algae and cyano basically clean the water for you, while removing what you can intermittently. When it settles, make sure that your change water is a good quality. I would not try dosing Kalk to manage phosphates - if the alkalinity consumption is not there in the tank to compensate, you'll just drive the pH too high. If you really want to target phosphates, then you can use GFO (granular ferric oxide) or some sort of phosphate binder. The first step, though, is to really take a look at and re-evaluate your feeding regimen. It's likely that it's too much.

[dkordella]

Hi Tom, thanks for the reply!

 

Honestly, I feed the fish maybe three times a week and then only a small amount. If it was just the damsel I wouldn't even do that. I understand about the Kalk and I'll hold off on that. I have a decent amount of coraline algae on the glass on rocks, but no corals. 

 

I run carbon through an old hang-on filter.

 

From time to time I'll get a burst of macro algae growing out of the live rock, but it tends to get quickly overgrown by the cyano...

 

I suppose I could also cut the lights off for a few days then do a series of water changes (once I get my new filters for my RO unit installed). But I'm now seriously wondering about the substrate in the bottom. Is the conventional wisdom now to have a substrate or go without? I'm thinking my substrate is just trapping debris...

[smallreef]

Sand is not normally a significant source of nutrient holding...

that being said you could easily pick up a 'gravel vac' and use that when doing water changes, pulling up the Cyano that s sitting on top of the sand...what else are you using for water movement in the tank?

[gmerek2]

I would buy a 10g tank and remove the fish to it temporarily so you have no bio load. Cut lighting time a few hours or just turn it off and do massive water changes. Cyano has a hard time growing where there is sufficient flow so try that also. Sorry Im new so someone please correct me if these are bad ideas.

[dkordella]

Thanks for the replies everyone!

 

I may look to replace the substrate. It's not sand: it's an arogonite "gravel" with the particles about 2-5 mm in size. It's too large and coarse for sand sifting critters, and that may be a part of the problem. I'm also going to cut the lighting back for a while as well as do a series of water changes. 

 

I also have new filters for my RO unit on the way (from Buckeye Field Supply). So hopefully between all of these measures I can get this thing licked!

[YHSublime]

I may look to replace the substrate. It's not sand: it's an arogonite "gravel" with the particles about 2-5 mm in size. It's too large and coarse for sand sifting critters, and that may be a part of the problem. 

 

I found your run of the mill starfish will find a way.