Hello all,

I have an ongoing BGA problem that has just grown up and copped an attitude.

I have a 20 gallon planted tank, set up for 6 months after tearing it down to move ( BGA was present previously) 20 gallon whisper filter, heater, plants - 1 crypt wendtii and dwarf sagittaria, substrate is medium gravel with a dusting of peat on the bottom. I have one betta fish, nothing else, fed a couple betta kibbles once a day. Water is 0 ammonia, 0 nitrates, 0 nitrites, ph 8.4. I use Jobes pond fertilizer sticks under the gravel, no liquid ferts. Lighting - 2 T5 6500 K 14 watt bulbs and a 15 watt fluorescent, 43 watts total. I vacuum the tank once per week, about 20% of the water.

I changed it yesterday and put some new fert sticks in, today the BGA has blown up to smother the tank and everything in it, and there was a horrible rotten egg smell ripping out of it. It was so bad my eyes burned. The gravel, the plants, the walls are completely covered in BGA algae, and something that looks like black brush/black beard algae. I immediately changed 50% of the water and vacuumed the gravel, which has gotten rid of the smell for now.

For a while I had a lot of green hair algae growing, which seemed to be out competing the BGA, so I let it grow. The Plants were growing and sending up sprouts. Now the green algae has died back and the BGA taken over, and the plants are turning brown.

I'm not sure what is causing the BGA algae explosion or where the hydrogen sulfide is coming from. I understand BGA can thrive in low nitrates because they out compete the plants, but the plants are getting nitrate, phosphates and everything else from the substrate ferts, not the water column. This shouldn't be an issue should it? I stir up the gravel regurarly when vacuuming, except where the fertilizers are, so it should be aerated. I thought maybe some of the old ferts leaked out of the gravel and caused the algae bloom, but what would cause the rotten egg smell? I'm worried about my betta fish, he's living in a rotten egg and algae soup, which can't be good for him.

Does anyone have any suggestions? I've run out of ideas and need some help! Sorry for the long post, I didn't want to leave anything out

pond fert sticks are potent ferts, they are meant for large quantities of water not a 20 gallon tank. Pond stuff is measured out by the 100's if not 1000's of gallons and well good example, I have the pond melafix at work, its 5ml per 50 gallons now for the aquariums its 5ml per 10g big dosage difference.
Id stop use, if not tear down the tank and start over or just do PWC's every 2 days till its gone. I do believe BGA cant be cured with a blackout either

I am sure the tank is loaded with that stuff, if you use any tabs use flourish they are no brainers.

When a large pond stick dissolves it will release its nutrient into the gravel but that eventually gets dissolved into the water if it is in excess....which it surely is. Hair and string algae thrive from excess nutrients.

BGA typically blossoms in low nitrate. Did you measure for nitrates after adding the fertilizer stick? Not knowing the make up of the pond stick, it might also contain sulfates resulting in H2S gas under the gravel. Do you have a link to the fert stick? If your nitrates are in fact low, you need to just use ferts that are intended for an aquarium. I would suggest Flourish in liquid form. The betta alone is not adding enough nitrate to your water.

On top of all this the amount of lighting you have on a 20g tank is way too much unless you are using CO2. Those T5 lights are much stronger than your typical fluorescent bulb.

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--->Pictures of my 75g Amazon tank<----

Hello again,

Thanks everybody for the suggestions. Per your questions, yes I use Jobes spikes for aquatic plants 8-24-8 (JOBES AQUATIC PLANT FERTILIZER SPIKE 6305 JOBES/ROSS I think I got overenthusiatic and used way too much, so I cleaned everything out and did 50% wc which got rid of the rotten egg smell and it didnt come back, I have one tiny piece underneath my crypt. Bought some KNO3 and made up some PMDD, Nitrates are ~5 now, they were 0 before when I tested, which was part of the BGA problem I'm sure. I dose Flourish micros 1x per week.

Bought a powerhead which is giving some nice current around the substate, the BGA doesn't seem to like that though it hangs on. Recently bought some anubius which seems to be doing well, nothings turned brown and died yet. I'm starting a 3 day blackout, cleaned out as much crap as I could, did a 50% wc, dosed KNO3, and covered the tank, we'll see if that helps.

As for lighting, I didn't realize that was high? I have two T5s which are 14W each and one 18W fluorescent plant bulb (walmart variety) Thats 46W, 2.3 wpg, isn't that medium light? I didnt think co2 was strictly necessary, though its kind of on the threshold. Anyways now its about 1.6 wpg, I can't afford the expensive bulbs right now (empty pockets) which are like $20 a piece plus shipping so I'm going back to lowlight as my expensive bulbs expire.

So I'm doing everything I can think of, if anyone has any ideas what I could do different or helpful I would appreciate it. I've been battling BGA for years (unsuccessfully) and I'm so so sick of it.

Can you check your phosphate level? no nitrates, high(ish) lighting @ > 2wpg and not enough plants to do battle. Are the sags and the crypt the only plants in there? Slow growers. Algae play ground.

Cut out the plant spikes for now. You don't need CO2...but the sags will love you for it if you do.

Yeah as I mentioned above T5 HOs can not be compared to noramal bulbs at a watt to watt comparison. They are stronger and have more penetration power (lumen). Anything over ~1-1.5wpg for a T5, I would consider CO2.

If you want a 1 time "reset" of your BGA and it is this slimey "algae", you do have the option of treating it with antibiotics. BGA is actually a bacteria and can be killed, however keep in mind that this may also destroy some of your beneficial bacteria, so if you go this route, save your current filter media or replenish your bacteria by some other means so you don't have a mini-cycle.

Another option is to completely blackout your tank for about a week. Start with a water change ~50%, change filters, blackout, do not feed, after ~5 days, vacuum the BGA with another larger water change and your tank should be BGA free.

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--->Pictures of my 75g Amazon tank<----