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Starry 02-19-2013 11:16 PM

Help me ID this algae... BGA?
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Is this BGA? It's mostly on top of the water. It's dark and slimy, and generates millions of pretty big bubbles (no, the bubbles are not coming from the plants). It doesn't cling to plants tightly, it actually comes off very easily if the plants are disturbed, and then it floats around as small black strigy bits. I don't notice a strong smell. I've been trying to get rid of it for weeks, it keeps coming back. It started at the same time as a bout of green water. A UV sterilizer cleared up the green water, but this stuff has been tenacious. I have lots of light, lots of pressurized CO2, and have been dosing my usual ferts regime, with water changes (almost) weekly. I'm about to try erythromycin, so I want to make sure that it actually is bacteria. I swear, in my 11 years of experience with planted tanks, the one thing I've learned is that as soon as I'm done battling one type of algae, a new kind comes along. I can't believe that after so many years there are still new types of algae for me to discover!

Adam C 02-20-2013 12:12 AM

When was the last time filters were cleaned? What are your dosing, light, and w/c regiments? What does "lots of pressurized co2" mean?

Starry 02-20-2013 12:35 AM


Originally Posted by Adam C (Post 2591930)
When was the last time filters were cleaned? What are your dosing, light, and w/c regiments? What does "lots of pressurized co2" mean?

I have a HOB filter with two sponges. I replace just one at a time, whenever I feel like it, probably every 2-3 mths on average.

It's a 10 gal with 40 W CF light, bulb was changed a year ago. Dosing NO3 to ~15 ppm, PO4 to ~1.5 ppm, 1/4 tsp KCl, plus traces as per directions. Sometimes a bit of iron. I admit I'm bad at doing the mid-week dosing, so the nutrient levels do get low, it's my bad. I also have way too many fish, so there's a ton of fish waste. Fish have always been healthy, not a single illness or unexpected death since I've been keeping these fish, over 10 yrs. Lots of plants, including some fast growing ones. Pressurized CO2 is 2 bps, with a sprial ceramic diffuser. I don't have a drop checker in there anymore, but I know that this rate results in a "green" range (and I did use proper 4 dKH water that I made up myself). I just lent my drop checker to someone, that's why it's not in there anymore. Plus, it collects algae and looks ugly.

hope this helps :)

Adam C 02-21-2013 01:23 PM

IMO, I would do a large 80%-90% water change and do a very thorough cleaning, ie clean filters, gravel vac where you can, remove as much of that stuff as you can, and reset dosing. Also, you do not need to toss old filter material, so long as you clean it to prevent reductions in flow and its not falling apart.

How long is your lighting cycle? Have you checked nitrates recently?

Starry 02-21-2013 10:04 PM

I've already tried the tank "reset." Nitrates are 10-20 ppm after I dose, then go down to 0 throughout the week, as does PO4. I should really keep on top of the mid-week dosing.

So is it BGA?

Adam C 02-21-2013 11:47 PM

I couldn't tell you based on what I know. But I will say that it def. sounds bacterial. The EM might work, but it might not. Even if you kill it however, you need to address why it (continuously) showed up.

Keep up with dosing and w/c or dial back on the lights if you cannot dose midweek. Running short on nutrients in a high tech set up can definitely cause issues really fast. Remember, its not the most abundant nutrient affecting plant growth, its the least abundant.

If your tank never gets a chance to "beat" the bacteria or algae over the long haul, each week its getting a chance to come back.

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