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Algae questions

Nov 27, 2002
As I've mentioned in my Tank Crash thread, my tank has thoroughly recovered and is again humming along. Yet I would not be willing to say it has PERFECTLY recovered. An odd "problem" exists.

Before the crash, the tank's algae population had stabilized into a balance between coarse hair algae (regularly plucked, not to nuisance status) and some large macrophytic leafy alage, growing healthily...possibly a type of sargassum. Since the crash, the algae population is behaving very differently. The macrophytic algae is alive and growing, and appears healthy, but is growing MUCH more slowly than before. The hair algae seems almost dormant.

The biggest "problem" is a slimy brown algae which is consistently trying to coat my sandbed. I can siphon it off one evening and have it completely regrown the next...indeed, in a matter of a few hours (when the lights are on) it recovers the sandbed. It's not overgrowing everything, though it does slowly grow on the glass, and patches of it cling occasionally to the live rock. My first thought was that this is cyanobacteria, yet...is that typically a dark brown color? Some research is suggesting to me that these are diatoms, yet upon very close inspection I can see a (very very fine) filamentous, netlike structure to this stuff. I thought diatoms were essentially individuals, and for that matter need silicates...what about a tank crash would have introduced silicates?

Ideas on how to cut down on this? I've seen some suggestions...a good sand-stirring critter, siphoning algae away regularly (but it comes back so FAST!), making sure nutrient levels are low. I recognize that my nutrient levels could actually still be higher than normal, and that this algae is merely sucking it up to keep it undetectable in the water. Would my best bet, then, be to keep siphoning the algae with the theory of removing them = removing whatever nutrients they're gobbling up so rapidly? Would these guys be what's causing the changed growth patterns in my other algae, or is it rather the tank condition causing the bloom in the first place that's also holding back the other algae?

And a note on sand-sifting critters...my previous sand-sifting star did, I thought, a great job, and was very active. My new one seems far less active. It also is capable of climbing glass, which I thought the "sand-sifters" lacked the suction cups to do. I can't really tell a species difference, but perhaps this is the "wrong" one?


Just noticed that in a previous post, George said that polyfilters aren't too great at removing silicates and phosphates. My water pretreatment is a carbon/polyfilter combination...perhaps with my massive water changes and pretreatment system, enough of those nutrients snuck in to feed diatoms--through normal minor water changes and makeups these nutrients would get depleted too quickly for a bloom?

Hey rusty:

Brown diatom algae seems to be a problem that most tanks develop during (or slightly after) cycling. You may want to try a phosphate "sponge". I think that you are on the right track. Having "good" macroalgae in the tank will generally control it. You may want to add some Caulerpa. It seems to do a good job soaking up nutrients used by "nuisance" algae.

I would continue what you have been doing, ie. removal of algae, and try the phosphate sponge and some "good" algae. If your LFS doesn't have any you can usually find some on ebay. In my experience the type of algae growth that you are experiencing will generally die off pretty quickly after the excess nutrients have been used or taken up in another manner.

Oh Yeah, Make sure that your skimmer is working correctly. Good luck, hope this is of some help! :madsci:

THanks. Skimmer seems to be working fine. Don't have Caulerpa...have what is probably a type of Sargassum. I like it a lot, but it DOES produce a lot of mildly organics. Ihave to keep it trimmed back due to that. I believe I can get some Caulerpa locally.

I've tried a LOT of research on PolyFilters, and come up mostly empty. I know much of what they remove, and that from experience they're quite adequate for my tank, but full detail on what is and isn't adsorbed is impossible to come by. The manufacturer doesn't (perhaps understandably--why highlight whatever deficiencies you might have?) provide incredibly detailed data, and no one else has full, easy-to-interpret testing that I've been able to find. I did find that it apparently does remove phosphates, but only removes some types of silicates.

I'll fiddle with these idea some more...thanks again.

Hi rusty

Chances are this outbreak will pass. A tank seems to go through various stages and with that comes various algaes and diatoms etc.

I have always had a lot of caulerpa in my marine tanks and i can say that this seems to out compete the rubbish algaes :smile:

Have you tried testing for silicates and phosphates? From experience with a bad algae outbreak on a very large tank I maintain, it was the silicates that were causing the problem as nitrates and phosphates were virtually nil. We tried to get round the problem with several large water changes using RO water but it never made a difference and in fact probably got worse.

What eventually happend was that we let the algae grow and trimmed it like you are doing. Eventually the algae removed whatever it was it was feeding on in the tank and started to die when the resource was depleted. This was confirmed when it was almost gone and a water change was done and it came back again. Second time round and with a bit more patience it dissapeared and hasnt come back.

The most algae free tanks that I have seen are high in calcium 450 - 500 ppm and also have a refugium with caulerpa. The high calcium lets the corraline algae outcompete the other algaes...

The joys of aquariums eh?

I've heard before high calcium is a discouragement for the problem algae. With corals, I guess that's a good idea anyway (or so I've been reading...I was originally thinking I wanted calcium around 360 or so but I've been finding that's much too low.)

I don't have a silicates test...though as you point out, perhaps the best way to remove them anyway is through algae harvesting.

What sort of calcium test are you using? I'm using the one that came with my SeaTest kit, and though I don't really dislike it, I've wondered if it's maybe a bit vague--it's a titration, "count drops until you see the color change fully" sort of test.

Hi rusty,
yeah its the same type and i do find them a bit vague too! :frown:

the one i use is saliferts calcium test and i prefered that to the other one i used which was Hagen's. But that is just personal choice. So now i just stick to what I am used to.

Are you adding calcium at present? I dont think i ever actually ued it on a ceph tank. regular water changes should keep it quite high and since i have never had any SPSs or clams etc i havn't needed it too high.

What's your lights and schedules on the tank? Perhaps the bulbs need changed as they produce different light as they get older??? Perhaps that is encouraging algae?
I'm thinking (at this point) that the problem is a combination of things, but that the key is the crash "resetting" the nutrient and algae balances in the system...that the diatoms got an opportunity with the death (?) of some algae and the shift in nutrients. Plus, my massive water changes which easily would amount to at least 2-300% over a week's time would have introduced more limiting nutrients (silicates, etc.) than were usually present, presuming my prefiltration can't remove those. Oh, and there's the critters that died off...my former sand-sifting star was much more active than my current one (which I suspect is another species) and I most of the plentifulf near-microscopic crustaceans in the live rock, which perhaps ate diatoms.

I am adding calcium now. I wasn't before, really, but that's because I thought 360 or so was okay. My water changes tended to keep it around there. Because I have some corals (and would like to have more) and would like to encourage coralline, and in light of the suggestions that higher calcium can help with some algae, I've started gradually raising over the last couple days (algae bloom's been for a couple weeks at least.) Learning how to add calcium has been an education in itself...I'm not willing to fiddle with Kalkwasser, so I've ordered a two-part supplement and am using some gluconate until it arrives.

I'm actually considering lengthening my light schedules...I've found many suggestions it should be more like 10-12 hours for corals, and I've been using about 7.5. I understand that can be a double-edged sword...the "good algae" and the "bad algae" would both like more light.

I've heard consistent reports that bulbs shift spectrum toward longer wavelengths over time. Mine are (best guess) halfway through their life, so that could be an issue. I'm using 4X55 PC fluorescents, which are rumored to be much better about shifting. In any case, unless the problem's unbearable, I don't really want to try replacing them, since they're $20 a bulb.

Of course, this tank's such an exercise in compromises. With an octopus, nutrient levels will be that much higher anyway, so I have to be sure my bioload is low and my octo relatively small for a 55 gallon tank. And in order for the tank to be attractive and not JUST a cephhome, I want corals, yet an octo doesn't like the lighting they need...so I've had to ensure lots of dark hiding places in the live rock (thankfully it's very craggy and porous), and am contemplating some sort of "octohouse" that would be near pitch-black inside. Gollum seemed to have no trouble with the lighting, aside from the obvious hiding when they were on...although, even then, it seemed his hiding was based on seeing me. When I did catch him out, the lights had on a couple occasions been on for some time, and he only bolted when he realized he was being watched.

Sounds like you'll get on top of it.

did you not fancy the pre-made calcium liquid additives? Some of them also have strontium and iodine for the corals?

Also i think that you are right about what started it
I think/hope you're right. Bloom has seemed progressively milder last couple nights.

At this point, I'm using a pre-made liquid ("Reef Calcium," a gluconate I think) because I didn't know much about calcium maintenance. Now that I've finished a good coral book and done some more online research, I've found out what's available. The most attractive options to me are the pre-made liquids you mention (most likely calcium gluconate, syrupy and highly concentrated) and the liquid two-part additives.

The gluconate has some vague allegations of encouraging algae, though ironically I haven't used it much at all until the last few days, when the bloom seems to be petering out anyway. Biggest drawback is that it apparently does not balance out properly with alkalinity, which can limit the peak calcium levels in the tank.

The two-part liquids are what I'm going to use, because they can maintain a proper balance of alkalinity and calcium, which supposedly is a good thing. Only drawbacks mentioned are that they may also have trouble boosting an already low calcium (as in, add too much and it'll just precipitate out) and are expensive. I figure I probably make them work well for me, since I just want high calcium, not a religiously maintained specific level. And, as I'm not running a humongous reef tank I'm hoping price is not nearly as much a problem for me--plus I found a ridiculously good clearance price on 128 oz. bottles of the stuff which should hopefully last me a LONG time.

Kalkwasser (CaOH dissolved in freshwater) seems a real pain...you have to add a LOT of water to keep calcium up, my tank's just not that big...plus it reacts quickly with CO2 into carbonate, unavailable to corals, hence storage is an issue. And ideally you use a doser of some sort with it (expensive!). There are some other things but they too all seem to have drawbacks I'd rather avoid. So, I'll be playing with this two-part stuff...I think for a semi-serious-at-best coralkeeper, that'll do fine for me.

I use a two part product called "B-Ionic", and it works well...easy to use also! Have you tried Turbo snails for the algae problem? I had some in my reef tank and the cephs never seemed to bother them...and they took care of the hair algae...hmmm. Unless your octo likes escargot?:}
Whether your turbo snails will survive seems to depend on the individual octopus. One of the first things my little bimac did when he arrived was to eat all the snails, including a large turbo.

without garlic and butter?:smile: I talked to another reef enthusiast this morning, and he said the same thing as Nancy...gone in sixty seconds! I hope the buffers work out for the hair algae...it is such a problem. I must have been lucky with my little octo...he never bothered them. I suppose you could take a five dollar chance though...
Hehehe...considering that an octo itself is kinda the definition of a "sixty-dollar chance" I'm not specifically averse to such experimentation. I do have a few snails, but have avoided a platoon of them due to general reports of ceph snacking.

I did reintroduce some amphipods recently...I'm hoping they might have some impact. Not precisely sure what they eat, but teeny diatoms would seem logical?

The amphipods will eat anything they can get their mitts on! I have seen them trying to drag crab carapaces away with them under the rocks.

Not sure if they will make much of a difference to diatom algaes though :frown:

Is a refugium a possibility for you? (an alage scrubber?)

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