Blue-Green Algae takeover - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 8 Old 03-23-2014, 11:55 AM Thread Starter
Blue-Green Algae takeover

My 20gal long tank has had a really nasty blue-green algae problem for the last couple of weeks. When I do the weekly water change, I pull out as much as I can find, pull it off the plants, scrub down the glass, and by the next week, it's taken over so bad you can barely see through the glass again.
It's a 20 gal long tank, peat moss capped with black sand.
My current Fish are:
1 clown Pleco
3 kilifish (flag fish)
5?(6?) Platys (they keep having more....I think there's probably at least four or five tiny babies in there with the 5 adults and the one half-grown one)
1 African Dwarf Frog
2 Amano shrimp (they were a mistake. I'd drained the tank almost completely a few weeks back looking for my pleco, couldn't find it and assumed the algae was from it dying and decomposing. the pleco popped up from wherever he was hiding as soon as I got home with the shrimp, the jerk.)
I'm pretty sure my tank's overstocked....I kind of want to find somewhere to take the platys and possibly the pleco, but there's no one around that I know who keeps fish.
Current plants are:
swords (4-5)
ludwigia repens
some anacharis? I pulled a lot out recently as it was too densely planted for the fish to get through that part of the tank.

Unfortunately my testing kit's gone missing so I don't have the water parameters just now. I'll find that and test the water some time today before I do yet another water change. will post the results before tonight with any luck.
My usual maintenance is a ~50% water change, and vacuuming the debris off the sand weekly.

I'm a student, so my current plan is to try and keep everything alive until the summer, and once I have time for the undertaking, completely break down the tank and replace the peat moss with soil, replant everything, cycle while my fish are temporarily housed somewhere I haven't figured out yet, and hopefully not have to buy 100% new plants.
If anyone has any suggestions to that end, I'd be happy to hear it though, or better ideas. keep in mind that anything that's going to take constant monitoring or daily testing is going to have to be put on hold till about june, and anything that costs more than ~$20-~$30 is going to be hard to swing, as I'm not currently a productive member of society.
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post #2 of 8 Old 03-23-2014, 05:43 PM
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Blue-Green algae is actually a bacteria (cyanobacteria) and kind of hard to get rid of. It can be treated with 200 mg erythromycin phosphate/10 gallons water, which is a medicine but may effect your beneficial bacteria so should monitor your cycle for a few weeks after it's used.

You can do a water change and then black the tank out for 3 days, then do another water change.

Causes are to many excess nutrients in the water column, Anaerobic conditions, High levels of organic wastes, Excess Light or you brought it in from a new plant or object put into the tank. You can keep manually removing it with frequent water changes to eliminate the excess nutrients. Put Purigen in your filter and maybe some Phosguard as well.

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post #3 of 8 Old 03-23-2014, 05:56 PM
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Check with your local PetCo not PetSmart. I had a Gourami and some Tiger Barbs but wanted Angels and these fish are incompatible. My local PetCo took them in for adoption which means that these fish are available to customers at a lower cost than buying from the regular stock.
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post #4 of 8 Old 03-23-2014, 05:57 PM
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Petco has a policy to never turn an animal away actually.

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post #5 of 8 Old 03-23-2014, 06:09 PM Thread Starter
Will the erythromycin phosphate bother the shrimp or the frog? (or the pond snails to a lesser degree, but I don't care for them as much, as they hitchhiked in on one plant or another)
Couldn't find the testing kit...I'll have to keep looking, since I'll want to keep an eye on that while I dose the tank.
I might try the blackout next weekend, fri-sun, but will the plants survive three days of no light?

RE: petco, I'm not so sure about it. The local one's fish department is really incredibly gross and poorly managed last time I was there; dead fish in the beta cups, rude employees, so on and so forth. I'll have to drop by and see if there's any improvement before I'd leave fish there. There IS a petsmart nearby with a better fish department, and an LFS that may take them, but the LFS doesn't normally carry platys.
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post #6 of 8 Old 03-23-2014, 06:46 PM
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I would check with the LFS first because PetSmart doesn't take fish unless you find an employee who will take them to their personal tanks.

If your water is blue-green as you say you may not get accurate readings on your liquid test kits as they go by color. See what I'm saying? I would suggest that you get some test strips. My guess is the strips wouldn't be effected by the color of the water. Anyone else agree?
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post #7 of 8 Old 03-23-2014, 07:00 PM Thread Starter
the water is perfectly clean, when you can see it(granted, stained brownish from the peat moss, but in small samples it's clear), it's that the algae climbs the walls of the tank and covers the plants until it looks something like thick green cobweb.
I've been told test strips aren't as accurate? they're not as expensive as buying a new kit, so if need be I can grab some when I go looking for the medicine, so long as it's safe forthe shrimp.
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post #8 of 8 Old 03-23-2014, 07:36 PM
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I don't know if it's shrimp safe from personal exp but trusty google says it is -
Erythromycin & Shrimp (Cherries) - Shrimp & other Invertebrates - Aquatic Plant Central Discussion Forum • View topic - Cyanobacteria (BGA), antibiotics, and cherry shrimp

The plants will survive the 3 day black out just fine, much more so than continued blankets of BGA growing on them.

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