Green thread algae: N:P ratio and/or Fe/trace buildup the culprit? - The Planted Tank Forum
 
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post #1 of 12 (permalink) Old 03-02-2005, 03:44 AM Thread Starter
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Green thread algae: N:P ratio and/or Fe/trace buildup the culprit?

Howdy folks,

I began dosing 0.1ppm Fe at water change time, and 1-2x during the week maybe 3 weeks ago. Since around the same time and until about a couple days ago, I was also mistakenly underdosing NO3. Also, have been dosing flourish 1 capful 2-3x/week.

75gal
Light = 4 x 65W
KH = 3
pH = 6.3
K+ should be about 20ppm (theoretical)

Water change is about 40% per week with tap.

During the past few weeks, my PO4 has been about 2-3ppm (comes in tap water) and NO3 anywhere from undetectable to 5 ppm.

I suspect that a low N:P ratio, and possible Fe and trace buildup have led to a bloom of green thread algae.

Questions:
1.) is that assumption correct, and am I therefore doing the right thing by dosing NO3 to 15ppm and discontinuing Fe/trace for a while?
2.) Should I be more aggressive, and do a large water change with RO water (I have a unit) whjle keeping an orthodox N:P ratio?

Best regards,
Trapper

75g planted: flourite, XP3, 5lb CO2, pinpoint controller, DIY reactor,Amiracle skimmer box, 10g sump with 2 x 300w RENA heaters, 9W jebo UV, rio 1700 pump, 4 x 65W 10k/6.7k.

"It is a mitzvah to be joyous always." -- R' Nachman of Breslov
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post #2 of 12 (permalink) Old 03-02-2005, 04:17 AM
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I wouldn't mess with the RO.

Your CO2 looks to be @ 45ppm if your tests are correct.

Your NO3 is way too low, & in my opinion is the culprit here. You definitely need to add nitrate to the tank. I'd work it up to ~15ppm.

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post #3 of 12 (permalink) Old 03-02-2005, 10:20 AM
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I too have a growth of thread algae in my new tank that's been set up for just over a week. (80 litre - see sig)

Parameters;
Photoperiod = 12 hour
Temp = 25.8C (steady photoperiod increase from 23.5 to 26.5)
pH = 6.97 (fluctuation range = 6.89 - 6.98)
KH = 10dKH
CO2 = approx 33 mg/l
GH = 13dGH
NO2 = 0.5 mg/l
NO3 = 7.5 mg/l
NH3 = 0 mg/l
PO4 = 0.7 mg/l

There are 25 stems of Hygrophila polysperma & 25 stems of Rotala indica in there (growing and branching like mad!), as well as three small marimo balls.

I have not added any ferts of any kind yet. Is it about time to add something to balance the tank?

Any advice?


Eheim Pimp #121

80 litre "Planted" tank
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post #4 of 12 (permalink) Old 03-02-2005, 03:49 PM
 
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I wouldn't back off the trace, you don't want another nutrient to be limiting your plant growth. Traces do not cause an algae outbreak. Just add more nitrate as was suggested, but it doesn't have to be a rigid 10:1. You can be off a bit, because after your water change your values will be lowered (except your phosphate) and you can start over again (Estimative Index). You can go with a larger water change if you want. Add more stemmed plants if you need to to compete with the algae. These things take time so have patience. I have to remind myself of this all the time.
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post #5 of 12 (permalink) Old 03-03-2005, 10:48 PM Thread Starter
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Gents,

Here's (1) what I did a couple nights ago; and (2) my current water params; and (3) my observations so far; and (4) what I'm planning to do.

(1). I drained 30 gals from my 75 gal/7gal setup, replaced with RO water. Dosed a changewater's worth of Mg, dosed K, Kent humic, dosed *tank* NO3 to ~15ppm. Did NOT dose PO4, Fe, or traces.

(2) PO4 between 0.1 - 0.25 ppm. NO3 >12.5 ppm. KH 3, GH 3, pH 6.3, [CO2] 40something. Fe, K, traces not tested.

(3) Green thread algae is still growing. Fish are happy (glowlight tetras are spawning, in fact). Plants growing.

(4) I plan to continue to snip off stems/leaves which have any appreciable GTA growth. I also plan to keep N:P about where it is now. Will hold off on dosing Fe and traces until the next scheduled water change, which is in 1 week from now. Other than snipping plant matter with GTA on it, I plan not to prune (since, so far, snipping the infected stems has amounted to roughly a pruning anyhow).


Someone mentioned that it's important to keep Fe and traces up. By mentioning in (4), supra, that I won't be adding these for a week I didn't mean to imply that I disagree with that principle. I'm just reasonably sure that after my water change a couple nights ago there will be enough left to last until next water change.


As always, comments are welcome.

Regards,
Trapper, in NYC

75g planted: flourite, XP3, 5lb CO2, pinpoint controller, DIY reactor,Amiracle skimmer box, 10g sump with 2 x 300w RENA heaters, 9W jebo UV, rio 1700 pump, 4 x 65W 10k/6.7k.

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post #6 of 12 (permalink) Old 03-08-2005, 11:18 PM Thread Starter
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Here's an update to what's going on to date:

Water params as described above, but the green thread algae still abound.

How long should it take for the stuff to start to lose out to the plants? My 75g is easily 75%+ full with plants.

--Trapper

75g planted: flourite, XP3, 5lb CO2, pinpoint controller, DIY reactor,Amiracle skimmer box, 10g sump with 2 x 300w RENA heaters, 9W jebo UV, rio 1700 pump, 4 x 65W 10k/6.7k.

"It is a mitzvah to be joyous always." -- R' Nachman of Breslov
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post #7 of 12 (permalink) Old 03-08-2005, 11:51 PM
 
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I'm willing to bet that your CO2 is a lot lower than you think it is. I'm gonna question your CO2 concentration. Kent humic is some sort of Peat extract which will lower your PH. This throws the whole PH/kh relationship chart thing out the window. Your ph reading is not accurate because the humic is acidifying the water. My suggestion is to increase your CO2 till you get some decent pearling 2-3 hrs into your photoperiod. Theres no need to use this humic product, but if you wish to continue using it you'll have to use the plants as your guide to co2 levels.

If you don't think this humic is lowering your ph, do a small test, throw some in a gallon of RO water and check the ph of that, I'm sure your PH will be way low.

Marcel
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post #8 of 12 (permalink) Old 03-09-2005, 02:33 AM Thread Starter
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I base my CO2 concentration on pH as measured by my pH monitor, and by KH as measured by a Salifert test. I'm using CO2 injection.

Of course humic acid consumes some buffering capacity. My observed KH is *after* addition of Kent humic. Furthermore, I assume, safely I think, that bicarb is the only buffer system of any consequence in operation in my tank.

And my plants pearl.

--Trapper

75g planted: flourite, XP3, 5lb CO2, pinpoint controller, DIY reactor,Amiracle skimmer box, 10g sump with 2 x 300w RENA heaters, 9W jebo UV, rio 1700 pump, 4 x 65W 10k/6.7k.

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post #9 of 12 (permalink) Old 03-09-2005, 03:34 AM
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Is this the long threads of green stuff?

I had an outbreak of it in both my 75 and my daughter's 20. Hers was worse than mine. I have two other planted tanks set up. The only thing these two had in common was that an occupant had had ich and I'd used sea salt when doing the salt treatment method. Her fish - an angelfish - had been harder to cure so her tank had gotten a higher concentration than mine. Both tanks cleared up with water changes (though now they have BGA - again, hers worse than mine, which seems to be resolving itself)

Coincidence? Somehow, I doubt it. I must add though that she is (or was) really bad about overfeeding (she came to me last week fretting that her fish wouldn't eat. I went to look and find myself looking at a stuffed angelfish. She'd apparently fed him half an hour before and was worried because he wasn't ready to eat again. If that wasn't bad enough, she tried several different foods before saying anything to me about it.)

I'm not real consistant with fertilizers (in fact, I backed off after the thread stuff) but I've started adding potassium. Last week, for the first time ever, I actually added nitrates.

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post #10 of 12 (permalink) Old 03-09-2005, 09:10 PM Thread Starter
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Yes, it's the long thready green stuff.

--Trapper

75g planted: flourite, XP3, 5lb CO2, pinpoint controller, DIY reactor,Amiracle skimmer box, 10g sump with 2 x 300w RENA heaters, 9W jebo UV, rio 1700 pump, 4 x 65W 10k/6.7k.

"It is a mitzvah to be joyous always." -- R' Nachman of Breslov
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post #11 of 12 (permalink) Old 03-10-2005, 05:35 PM
 
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who cares if your plants pearl? pearling only means you have oxygen saturation.
Your nitrate is way low. If your phosphates tend to be at 2ppm or above, keep your nitrate at 20ppm so things stay in balance.
and 6 days is not enough time to fully clear up an algae outbreak.
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post #12 of 12 (permalink) Old 03-10-2005, 07:11 PM
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replaced with RO water
You really live in NYC and use RO water? NY water is virtually RO out of the tap. Beats me why you would do that.

As for your algae problem, I think the soft water exacerbates the problem. Back off on your traces and Fe a little bit. Increase dosing of K perhap via K2SO4.

Andrew Cribb
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