Blue Green Algae - need help

[sns26]

Hi all,

I rescaped my main tank a few months ago and now that it's grown in I have what I think is a mild BGA problem.

The symptoms are a blue-green gooey film that forms slowly over time on the surface of the sand substrate and on some of the plants. It's sticky but fortunately relatively easily removed. I've inserted two pictures of the stuff as it exists on the substrate.

The tank is high-light, CO2, and daily dosed nutrients roughly on an EI schedule.

I've seen people say that BGA is a symptom of nitrate deficiency, but I dose a hell of a lot of nitrate already. I thought it might have to do with low water circulation, but I've tried blowing more water across the affected area, but it keeps coming back there anyway.

Any ideas?

IMG_2409.JPG (132.81 KiB) Viewed 9321 times

IMG_2409.JPG (132.81 KiB) Viewed 9321 times

[Jt731]

Tell us more about your lights, water parameters, and more about daily "ei". And are you dosing potassium as part of ei?

Almost all of my algae is new tank and too much light. From what I have read, bga thrives on too many nutrients and I'm wondering if you are dosing too much nitrogen and phosphorus.

[sns26]

I am currently dosing *more* than usual, on the perhaps mistaken assumption that deficiencies are what is getting me in trouble.

This is a reasonably well planted 57gal tank with medium high lighting (I have ~100w of DIY LED on tap, but I've dialed it down to about 65% of max).

I dose 9.3 ppm/day of KNO3 and 2.3 ppm/day of KH2PO4. That's more or less 2x what an estimative index calculator (e.g. http://calc.petalphile.com/) would recommend, but I had the same problem when I was dosing more like 5ppm/1ppm per day.

[krisw]

Seems like way too much, particularly given that most of the plants in your scape are not super fast growers, so the nutrient uptake will be less than an all-stem tank, for example. BGA can be a nutrient imbalance, both too high or low, or just out of whack. Like most algaes, if you have a nutrient sink in your filter or substrate due to lack of regular cleaning, your nutrients and organics may be even higher. If this is the case, do that maintenance -- siphon the substrate well, and clean the filter.

Otherwise, reset your tank with a 90% water change, and down-rate your dosing by 2-4X, see if that makes a difference. Also, given that it's summer, what's your tank temperature? If it's too high, it may inhibit plant growth and give a good avenue for algae to creep in.

If it's persistent, you can try a erythromycin treatment for a week or so, but keep in mind it'll come back if conditions are right. Also, note that erythromycin is a phosphate, so you may want to adjust dosing accordingly during this period, or just not dose at all...

[Jt731]

So I dose potassium in addition to the potassium phosphate you listed. And if the algae is bad enough, I dose Seachem Excel. 65W of LED seems excessive as well.

Why did you think you needed to double the EI?

[Cavan]

Improper ratio of N to P (too much P). Do a search for Redfield ratio.

As Kris mentioned, clean everything well. Clean filter monthly. Consider adding another filter. Clean that one monthly too. Get a surface skimmer if you don't have one. Aerate at night. Flourish Nitrogen is a superior nitrogen source; use that if you aren't already. More flow!

High light is fine as long as you have the co2 to back it up and some fast growers to balance things out.

[SCMurphy]

Maracin is your friend.

[sns26]

Update: no more BGA. I turned down the lights, turned down the ferts by ~3x, and put my CO2 as far up as I dare (yellow drop checker). I'm also trying to do more vacuuming: the new hardscape in my tank has really complicated my water circulation, and I'm getting a lot of gooey mulm settling in out-of-the-way spots. My old scape had a fair amount of mulm, but it never seemed to cause these problems.

One thing that did not seem to help was adding more circulation. More circulation sort of blew the BGA away, but it induced BBA! Out of the frying pan...into the fire.

The tank is now in slow-grow mode, which is right where I want it. I have a couple of stem placements that require trimming, but otherwise it's anubias, java fern, and crypts. I've come fully cycle in the hobby--now my view is "no perling, no problem."

[SCMurphy]

Keep siphoning up the mulm, the organics released from the decaying mulm promote the BBA. I like the catch phrase, probably because it describes what I promote. hahahaha

[Becca]

You could also get a few Amano Shrimp to just help keep algae in check. Batfish has some GINORMOUS ones in stock right now and they are great at cleaning algae off of plants. Plus, certain kinds of algae will cause them to change colors.