# Combat green algae



## htjunkie (Jul 20, 2012)

My tank has been established now about 2 months, went through a diatom bloom last month and now green algae is covering the live rock and sand. I have since cut down on the light. I don't have any corals now so I can definitely cut down on lighting.

Tank is 60G plus 29G sump, originally it was filled with tap water but since all water changes and top off have been RODI. 

Anything I can do to combat this? Should I just turn the lights off completely?

Thanks for your help. 

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## wildexpressions (May 3, 2010)

It is one way of doing it and I've certainly used that trick with some success over the years. 

It is important to pinpoint the cause(s) of the on going algae bloom and take care of them. If you don't you will be right back in the same spot a month from now. 

I usually unplug the lights and blanket the tank for 3 days. If you go that route make sure that your filtration is all up and running at its max ability because all of that dead algae has to go somewhere. You will need to do some water changes after it is over.


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## noy (Nov 19, 2012)

post a pic - not sure what type of algae you have (probably hair or slime algae).

The algae is feeding off nitrates and phosphates in your tank. Cutting off light will choke it off but it will return. Do some water tests (for nitrates/po4) and post your results. Doesn't sound like you have livestock so the nitrates/po4 may be locked in your live rock.

If you have a sump then set up a refugium with some macroalgae - it will consume the nitrates/po4.


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## htjunkie (Jul 20, 2012)

Here it is:


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## htjunkie (Jul 20, 2012)

I have 0 phosphate which I thought it was okay, but I believe it's the algae consuming so I'm not getting anything to register 

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## fesso clown (Nov 15, 2011)

htjunkie said:


> Here it is:


Hard to tell what's going on there. It took my tank about 9 months to go through various algea out brakes. I would suggest that you keep up on your water changes, watch how much you feed and try to manually remove as much as you can. Oh and be patient, eventually it will subside.


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## noy (Nov 19, 2012)

can't really tell from the photo's. if its a green staining - I wouldn't worry about it - that's fairly normal and may even be green coralline (see if it turns purple). From the staining in the substrate - I suspect this may be it. 

if its flaky and in sheets and blows off - it may be blue-green cyano - I would research (i.e. look at pics on the web) to make sure its really is. There are some specific meds for that (red slime) which is fairly harmless. But be sure before doing anything.


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## CRJ (Sep 7, 2012)

htjunkie said:


> My tank has been established now about 2 months, went through a diatom bloom last month and now green algae is covering the live rock and sand. I have since cut down on the light. I don't have any corals now so I can definitely cut down on lighting.
> 
> Tank is 60G plus 29G sump, originally it was filled with tap water but since all water changes and top off have been RODI.
> 
> ...


Honestly, if you have no fish or coral, restart with RODI. it will save you time and $$$. tap water is soo full of crap, clorine, cal, iron, iodine, that its the WORST thing you can put in your tank besides old tank water from another system.

you will be fighting phosphates and algae for a year before it becomes under control.

if your set on sticking it out, run GFO. ALOT of GFO. and run tons of carbon. filter the living snot out of that water for a good month or two. do a 50% WC with RODI if you can. that will drastically help.

I started with RODI from day one, and have never had a diatom or algae bloom ever, with the tank coming up on a year old and crystal white sand.


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## altcharacter (Jan 10, 2011)

Don't ever do a 50% WC with saltwater 
Just an opinion though...


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## htjunkie (Jul 20, 2012)

It's more like staining on the rock and substrate, I tried using a soft toothbrush (new one of course) to brush the rock and hardly anything come off.

I do about 10% water change every week, but I spread it in a week so one 5-gallon every 3-4 days. From what I have gathered, I should maintain the parameter swing as little as possible.

At this point, the skimmer seems to be stabled. In the past few months, I could not get it to leave the bubbles in the cup. It's either too much water in the cup and overfill or bubbles not reaching the cup no matter how I adjust the inflow. It seems to have fixed itself and now I can see the brownish stuff in the cup and I clean it every week or so.

I have carbon in a media bag about 5"x2", I replace the bag every month or so, should I be doing that more often?


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## noy (Nov 19, 2012)

htjunkie said:


> It's more like staining on the rock and substrate, I tried using a soft toothbrush (new one of course) to brush the rock and hardly anything come off.
> 
> I do about 10% water change every week, but I spread it over few weeks so one 5-gallon every 3-4 days. From what I have gathered, I should maintain the parameter swing as little as possible.
> 
> ...


It may be green coralline which is desirable (turns into the purple stuff).
I would not worry about it and don't bother trying to brush it off.

Changing carbon once a month is good and I wouldn't bother changing it any more often.


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## htjunkie (Jul 20, 2012)

Thank you, in general should phosphate register some number in the test? Mine is always 0 and I don't know if it's just consumed by algae?


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## Steel_Wind (Oct 26, 2013)

htjunkie said:


> I have 0 phosphate which I thought it was okay, but I believe it's the algae consuming so I'm not getting anything to register


My guess is that it is overwhelmingly likely you are measuring inorganic phosphate -- not organic phosphate. Testing for organic phosphate is an involved process most hobbyists are not set up to do.

It is not unusual to have inorganic phosphate levels very low (or essentially 0), while organic phosphates are still present and accessible.

If you are not running a GFO, your chances of 0 organic phosphates are very _very_ low.


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## htjunkie (Jul 20, 2012)

Ah, wasn't aware of inorganic and organic phosphate. I have the PO4 Phosphate Salifert test kit and that's all I use to test phosphate.


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## Steel_Wind (Oct 26, 2013)

htjunkie said:


> Ah, wasn't aware of inorganic and organic phosphate. I have the PO4 Phosphate Salifert test kit and that's all I use to test phosphate.


Yup. That tests for inorganic phosphate.


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## htjunkie (Jul 20, 2012)

In this case, reading 0 in PO4 test is a good thing?


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## Steel_Wind (Oct 26, 2013)

Sure it is. It's just not _conclusive_.

The point to take away is that it is not determinative of whether or not phosphates are available in your tank in terms of being capable of being able to be metabolized by various lifeforms in your tank, that's all.

You do need some of it - just not too much of it. Just because your test reads 0, does not mean it is not there in organic form.

Your pics do not seem to indicate hair algae, which is a prime indication of too many organic phosphates in your water, so -- could be worse.


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## noy (Nov 19, 2012)

Inorganic phosphate are what you need to worry about. If you don't believe me (not a problem - I'm just another dude posting in a forum) then you should believe Randy Holmes-Farley.

http://reefkeeping.com/issues/2006-09/rhf/index.php#3

The Salifert tests are among the best and you should get accurate results. I really think you are over-worrying on this issue.

I have no doubt algae is consuming the PO4 in your system and that is why you get a 0. PO4 levels are a simple question of import vs. export. The food you are feeding your fish imports phosphates. Right now your only means of exporting it is water changes. The excess feeds the algae. However, if your levels are measuring 0 - its still fairly manageable.

If you feel for cosmetic reasons you really need to choke off the algae. You can either - I) do more water changes, ii) run a refugium or iii) use chemical means to reduce it.

If you opt for iii) - I would highly recommend you just use Phosban in a filter bag and not run Granular Ferric Oxide (GFO) in a reactor - due to cost/benefit concerns.

hope that helps!


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## htjunkie (Jul 20, 2012)

Thanks for clarifying, I'm not too worried now after knowing what's going on. At this point, I'll leave it as I try not to use chemicals that I don't know and don't want to introduce other side effects.


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## htjunkie (Jul 20, 2012)

A different note, when I do water change, I use a water pump with a hose to pump water out of the sump, then put new water back into the sump. I haven't tried siphoning the sand bed in which I was told it's not needed and better not to disturb. My sand bed is close to an inch thick.


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## disman_ca (Nov 12, 2011)

There are other ways to clean the bed like a goby, snails etc. I siphon a little bit where I can and rely on a goby for the rest, others may not at all.


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## sig (Dec 13, 2010)

you should not disturb deep sand bad, but with 1" or little more I do it monthly

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