Help with algae overgrowth

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Aquarium Advice Newbie
Aug 31, 2009
Plainfield, IL
We have recently replaced our 75 gallon saltwater fishtank with a 210 gallon unit. We have:
150 lbs live rock
A variety of reef safe fish
Live sand bottom
Drilled unit with three jet pumps and main pump
Protein skimmer
An outer orbit hqi/t5ho lighting system.

We have a buddy that helps us with tank upkeep but we have run into a wall keeping algae under control. It is growing everywhere. We are considering a control unit for our light source and a reverse osmosis system. We have not checked the water for phosphate levels. I am a novice with reef tanks and any input would be appreciated in how to get this algae under control.
With your comments, it sounds like you know what you need to do... limit nutrients. If you're using tap water, a RO/DI system would be my first move. You mention a control unit for your lighting... are they not on a timer now? How long are you running them?

Is your skimmer pulling any gunk out of the water? If you aren't already, running some GFO (granulated ferric oxide) will help reduce/eliminate your phosphates and silicates if you have any in the tank.

How often are you doing water changes? And how much are you changing?

And yes... phosphate levels, as well as all other water parameters (nitrates, pH, etc) will need to be known to tell you what you need to attack.

Welcome to AA, by the way!
Thanks for the reply. Our timer is on the fritz so we do it manually for now- 6-8 hrs of metal halides and 8-10 hrs of T5s I think (I will ask our helper). Protein skimmer is pulling gunk out of the water. I also believe we do a water change once a month, 10-15 percent at a time. I will touch base with him as far was what our water tests are revealing.
I could be wrong.. but that sounds like you have the lights running for quite a while. Even with just the T5's they are pretty strong, and could be encouraging algae growth. Also, if you're only doing PWC's once a month, then i would say do larger water changes than that. I know people here who do something like 25-30% water changes once every two weeks.. so i think a bigger water change would be necessary since you only do it once a month.

If you have alot of algae growth then my guess is that you have alot of nitrates also. Maybe not a ton, but a good amount. If you have a sump/refugium, you could try putting in things like different types of macro-algae that will use up all of the excess nutrients in the water coloumn, that the algae would be feeding off of. If you don't have a sump/refugium, you could always just tie the macro to a rock and just let it grow and trim it as you need. These are some things i will be doing as well since i have a bit of a nitrate problem, which im sure will lead to algae problems. Hope this helps.
I think it would be helpful to list your water parameters?
SG, temp, Ammonia, nitrite, nitrate, PO3, PH...
A 10-15% water change once a month is one of your main issues. I'd consider 10-15% a WEEK a bare minimum if you're having algae issues - even then that's probably too little to help. It all depends on your water parameters.

What exactly do you have for fish? How often and how much do you feed? Are there corals in the tank?
We have a variety of reef fish (yellow tangs, clown fish). We feed once daily. Yes we have some corals. Our pH is at 8, nitrates near 0, we still need to test for phosphates.
Question: Would bio balls have any significance to algae build up?
We have a variety of reef fish (yellow tangs, clown fish).

I'm asking for your stock list because I'm trying to figure out if you're overstocked. A "variety" of fish just doesn't help us much. How many? What kind? If you're overstocked, that often leads to water quality issues that cause excessive algae. And if you're overstocked, it really makes it tough to get your water quality in line.

We feed once daily. Yes we have some corals. Our pH is at 8, nitrates near 0, we still need to test for phosphates.
Question: Would bio balls have any significance to algae build up?
Nitrates and phosphates are "fuel" for algae. Even though you have zero nitrates, I'd guess that's either an incorrect result, or you have enough algae that it's consuming the nitrates as fast as they're produced. (If that's the case, your phosphates will probably be zero also.) Only doing 10-15% water changes once a month... you're going to have nitrates. Bioballs aren't necessarily a bad thing, but they can pump a lot of nitrates into a system depending on the maintenance of the system.
We have one yellow tang, one striped moray eel, 6 damsels, 1 hawkfish, 2 clowns, one angelfish, one blue tang, an assortment of crabs and snails, couple mushroom coral, green carpet anenome.
Oh my.

I'm normally the conservative one around here about stocking, but I think most folks will agree that you're definitely overstocked with a 75g. Not sure if that angelfish is a dwarf one or not, but either way... too many fish. And that eel really want to be in a bigger tank.

I'm afraid whatever you do with regards to getting rid of your algae, with that many fish you're just going to be fighting a neverending battle. That's just a big bioload and it's just naturally going to create a lot of "excess nutrients" (nitrates) that algae will gladly consume.

Obviously some folks might have other ideas, but I'd say that you should probably reduce the fish load by 1/2, and start doing water changes weekly - or at most once every 2 weeks. Or learn to love the algae?!
Oops. I misread that original post. You have a 210 gallon... not a 75g.

OK... so ignore what I just wrote! You're OK with what you have in there... not too many fish. But I would expect that the moray is a pretty messy eater and big pooper. And with only one water change month, that's probably the source for your algae food.

I'd suggest going with the easiest things first - increase your water changes to weekly until you get the algae back under control. Start using RO/DI water. And manually go in and prune back/rip out whatever algae you can. See if the increased water changes don't slow down the growth.
Great advice, thanks. We purchased an RO filter and will begin weekly water changes for awhile. We currently try to manually remove algae as you suggest. We will see how things go.
Okay, RO/DI filter came today. I have the option of running RO water or a RO/DI water combo. Which option should I use?
RO/DI is the best option.
You can also slow down on the feeding. I'm not sure about the eel, but the other fish can be fed every other day.
What and how much are you feeding?
I feed every other day and sometimes skip an extra day, and have had not ill results in quite a few years.
Any chance you can post some pics? I'd love to see a 210G with those critters!
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