"Selective" algae growth

tanksalot

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Mar 11, 2006
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In my 90 gal. tank I'm seeing selective BBA growth. Some stem plants are looking terrific and algae-free, while other plants (jungle val., SOME crypt leaves, tank hardware) are heavily covered. Yes, I can and will trim off the growth, but my question is why? Why would some leaves (usually the older ones) accumulate algae growth but not others, and why some plants but not others?

Thanks

Tanksalot
 

Tom Barr

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Since BBA is heavily CO2 related, and some plants are more CO2 demanding than others, it's not surprising.
Generally the faster growing taller plants near the surface do better.

Why? They start photosynthesis faster/quicker and grab the CO2 1st, this leaves less for the other plants.

You need to add a little bit more CO2 SLOWLY till you see NEW growth of BBA stop.

Then you can kill it with spot treatments of Excel etc.
 

tanksalot

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Tom:

Thanks! That makes sense, especially since I've had quite a bit of growth in the last few weeks, as well as adding new plants.

I have a 90 gal. tank; 4 T-5's (right on top) and pH-controlled CO2 supplementation, using a Cerges reactor downstream of the return pump from a covered wet-dry. KH is about 3 -4. Prior to adjusting anything, I checked the pH meter calibration, and it was off by 0.3 - 0.4 (it was reading artificially low). Setpoint is/was 6.2. The drop checker (two bulb with a 4 KH standard) read a tad yellowish. Right now for the short term I'm going to let things go with a re-calibrated pH controller and see if the BBA growth stops, or do you feel otherwis

From what I've read on your site, I realize you're not a big fan of either drop checkers or pH-controllers, but there are many of us who don't have the keen eye for plant conditions that someone with your experience and knowledge has. Now I know to check CO2 if I see a wisp of BBA appearing.

But if you didn't have the experience you have, how would you proceed in adding a bit more CO2 to the tank?

Thanks for the help!
Tanksalot
 

Tom Barr

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Get rid of the drop checker and get a keener eye. :wink:

You simply add a tiny bit more CO2 and watch. Then repeat. Eventually you get the experience this way and without that, you really cannot someone specific ppm advice.
Algae, plant growth, fish, these are more relevant "test".

You just need to go slow and adjust, you can simply adjust the pH controller 0.05 pH units down and watch for 3-7 days, then adjust the same amount down again and watch closely.
 

tanksalot

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Well, I've learned quite a bit. I cleaned out a lot of the BBA and overgrown stem plants. Reset the pH controller and waited until this A.M. to see how things go before I plugged in the controller.

Someplace I had read on a forum a response to the question "At what level do you set your CO2?" and one of the responses was "until the shrimp start jumping out". I thought he was kidding......he wasn't. I couldn't figure out why the shrimp seemed so determined to crawl into the overflow, then I saw a cardinal in there and the light went on (in my head). Fortunately I didn't lose anything, and things are now stable. Other than re-calibrating the pH controller the only other change was a 40% or so water change.
It doesn't seem reasonable that I should have to run "so close to the edge" with CO2. Do you see it differently?

Now as far as I see my other options are Excel dosing and shorter photoperiod. I've got Excel on order.

Thanks
 

antbug

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Apr 4, 2011
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Can you raise your lights? 4 T5's right on top of the 90g is a lot of light. if not, I would pull one or two bulbs.
 

tanksalot

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Antbug: thanks!

I'd prefer not to raise the lights, since I sit next to it and don't want the glare. Taking out 2 bulbs is a good idea. I might try a much shorter photoperiod, say, 5 - 6 hours (it had been 12 hrs.).
 

aquabillpers

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Tom Barr;107338 said:
Since BBA is heavily CO2 related, and some plants are more CO2 demanding than others, it's not surprising.
Generally the faster growing taller plants near the surface do better.

Why? They start photosynthesis faster/quicker and grab the CO2 1st, this leaves less for the other plants.

You need to add a little bit more CO2 SLOWLY till you see NEW growth of BBA stop.

Then you can kill it with spot treatments of Excel etc.

I don't mean to sound argumentative, but I don't inject CO2 and the only algae I see in established tanks is the "dust" kind that is easily wiped from the glass. I haven't seen BBA in 25 years, when I didn't know what I was doing. Could "Increase CO2" just be a way of compensating for a tank management problem, like "Green water? Get a UV light."?

Bill
 

UDGags

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aquabillpers;108810 said:
I don't mean to sound argumentative, but I don't inject CO2 and the only algae I see in established tanks is the "dust" kind that is easily wiped from the glass. I haven't seen BBA in 25 years, when I didn't know what I was doing. Could "Increase CO2" just be a way of compensating for a tank management problem, like "Green water? Get a UV light."?

Bill

It's probably due to the difference in light. My bet is your tanks over the years have had less light. The OP has a considerable amount of light on his tank.
 

aquabillpers

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UDGags;108819 said:
It's probably due to the difference in light. My bet is your tanks over the years have had less light. The OP has a considerable amount of light on his tank.

Yes, definitely. Should the advice be amended to "Increase CO2 or decrease light? (This assumes that BBA is really light sensitive.)

Bill
 

tanksalot

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The 4-bulb T-5 puts out about 216 watts, which is about 2.4 watts/gallon. It's my understanding that that's not unreasonable. I DO have issues with "pearling mist" and would prefer a totally crystal-clear tank, so the lower light level would help in that regard.
 

UDGags

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Yes, definitely. Should the advice be amended to "Increase CO2 or decrease light? (This assumes that BBA is really light sensitive.)

Bill

In general you want to increase CO2 until you hit your livestock limit this way you're not decreasing plant growth by decreasing the light. If you still have issues after maxing CO2 you could decrease light intensity (or look at other factors-water circulation, water changes, CO2 fluculations). BBA is more directly related to CO2 than light.


The 4-bulb T-5 puts out about 216 watts, which is about 2.4 watts/gallon. It's my understanding that that's not unreasonable. I DO have issues with "pearling mist" and would prefer a totally crystal-clear tank, so the lower light level would help in that regard.

I'm guessing you are at high light (80-100 PAR) if the lights are right above (~26") your tank.
 
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tanksalot

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The T-5 fixture is directly on top of the tank. The bulbs are approx 2 inches or less from the water surface.
 

tanksalot

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It does appear that my lighting is excessive, and I also found this interesting lighting-related thread: .

So I can either take out 2 bulbs as Antbug suggested or lower my photoperiod to 4-5 hours or so. If I lower the photoperiod, (which I'd prefer to do) I suspect I run the risk of rapidly depleting the plant-available CO2 and inviting another BBA outbreak, especially in areas of lower water flow. I guess I'll try the 2-bulb approach and see how things go. I've got some Excel on order, and I'll treat all the Anubias and crypts, make everything pristine and try again.