# Green spot algae problems



## Altum (Oct 17, 2006)

I upgraded lighting on my main plant tank and now the glass and anubias leaves are covered with spot algae. It's mostly green, with a few black specks mixed in. It requires hard scrubbing or a razor blade to remove. I've always had a little in this tank, but the nerites were keeping it in check under the old lights.

I did a search here that suggests it's related to low phosphate but that doesn't seem to be the case in my tank. Can it be caused by low nitrate? I tested last night and I've got 2-3 ppm phosphate in the water, but less than 5 ppm of nitrate. I added enough dry KNO3 to take it up to 15 ppm. This tank is well-stocked and it looks like the EI powder routine is going need some N adjusting.

I'm running Nutrafin DIY CO2 (I only get maybe 15 ppm, though) and Flourish Excel. Pressurized CO2 is not something I can afford.

I'd appreciate any suggestions or things to look for.


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## banderbe (Nov 17, 2005)

Don't trust a crappy hobby grade test kit for making nutrient decisions in your planted tank.

I bet you do not have enough PO4. I can intentionally run my PO4 low, green spot comes every time, and the test kit will claim I have 2 to 3 ppm.

With full PO4 dosing the test kit claims I have over 10 ppm.


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## Zapins (Jul 28, 2004)

Sounds good so far. I agree w/ banderbe that the test kits aren't always accurate.

However, maybe your test is correct. It does take a decent amount of time for GSA to stop growing on new surfaces. In addition, adding more PO4 will not kill off existing spot algae, it just prevents new algae from growing.

Use the fertilator to calculate how much PO4 you are adding to the tank in each dose. At least that way you will have a rough estimation of how much is in there. Or just do a large 90% water change and then add all the ferts back in known amounts (using the fertilator to calculate ppm).


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## Altum (Oct 17, 2006)

Thanks for the answers. I guess I should go back to my usual philosophy of reading the tank and not the test kits.  

I've only barely started adding phosphate. Before I upgraded the lighting, this tank really didn't need N/P supplementation. It's pretty well stocked. I'll ignore the test kit and go to EI dosing.


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## MrSanders (Mar 5, 2006)

another thing to consider is that green spot can also be caused by low CO2 levels..... which sounds very possible with you DIY setup. You said Pressurized CO2 is not something you can afford and I can totally see where your coming from.... seems like its really easy to spend a lot of money with this hobby  

However there are other options you can use to get better CO2 values.... one right off the top of my head is to use a very efficient reactor.... I dont know what your using now to get the CO2 in the water, but I find a power reactor.... the gravel vac type.... to work very well... and can be made for just a few dollars if you have a spare power head laying around..... 

Also another thing to consider along with the above, is to add a few more soda bottles onto your Nutrafin unit.... you can roatate changing the mix and do one a week so you get a more consistant flow out of them

the last thing that strikes up an idea with me is to drop the CO2 all togeather and go with just the Excel.... however in the long run this may start to get expensive....

just a few thoughts to consider  good luck


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## Altum (Oct 17, 2006)

I was wondering about low CO2. I think I'm also seeing bits of nibbled-down BBA now, which fits. I've actually been using Excel all along in that tank, but my understanding is that Excel isn't quite as good as real CO2.

I like the idea of adding more soda bottles to the Nutrafin setup. I can just use an airline gang valve backwards, right? I'm using the ladder for the diffuser and it's working - there just aren't enough bubbles. The tank is only 15 gallons, so hopefully a powerhead diffuser won't be necessary. I think it would create a bit more current than the fish would prefer.

Thanks for the ideas.


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