# How to kill GSA, Any new ideas?



## BryceM (Nov 6, 2005)

So, I've had my "dream tank" going for over 18 months now. At present I'm thrilled with almost everything about it with one exception. I'm really seeing some excellent growth in species like R. macranda and L. senagalensis. HC is forming a decent carpet and most everything is going well. Some plants are growing annoyingly well.

Since overcoming a huge catastrophe with slime algae during initial setup it has been fairly stable. There is a random small spot of BBA here and there in the tank but it isn't noticeable except on the Cyperus helferi. Older anubias leaves show the usual spackling of GSA but I've never been too bothered by that - IMO, it actually has a "natural" feel to it. I got just a slight touch of thread algae a while ago when I slacked off a bit on dosing. Fortunately it went away promptly with closer attention to the fert plan.

What continues to annoy and frustrate me is GSA on the front glass. Every week or two it requires a good mag-float scrape down. Once that's done, it takes about a day for the water to clear up again. The slightest bit of turbidity shows up very quickly in a 6' long tank.

I'm using 100% RO water, doing a 20% WC three times per week, and alternating macros & micros every other day. I use Lamotte kits to test parameters and am currently dosing the following:

CaSO4 - 1.5 tsp after WC
MgSO4 - 1.5 tsp after WC
K2SO4 - 1/2 tsp after WC
CaCl2 - 1/8 tsp after WC
NaHCO3 - 2 tsp after WC
KNO3 - 2 ppm NO3 after WC
KH2PO4 - 0.6 ppm PO4 after WC

Flourish Iron - 30 ml on off days
Tropica Master Grow (or whatever it is now) - 60ml on off days

A couple of weeks ago the tank showed GH 5, Ca:Mg ratio of 3.5:1, KH 3.5, NO3 5 ppm, PO4 0.8 ppm.

Over the past 4 or 6 months I've gradually lowered NO3 from 20ppm to the current 4-6ppm. I also cut way back on PO4. GSA has not appreciably changed during any of this. Most of the plants have looked better since adding more K to the recipe about 3 months ago. GSA has been present from the initial setup and it's still there. I use a 15W UV filter 24/7.

Lighting is Metal Halide 150Wx3 with ADA 8,000k bulbs for 5 hrs/day, T-5 TEK reflectors 39Wx4 with a combination of 10,000k & 6,500k bulbs for 11 hrs/day. CO2 is controlled with a pH controller between 5.95 and 6.15 during the entire photoperiod. Pearling is INTENSE while the MH's are on.

My other tank is a 46g tank that I fertilize about once every 6 months or so. Plants there look slightly nitrogen & iron deprived but they grow well enough and have great color. I use pressurized CO2, SMS substrate, and fish food. That's it. The glass is always spotless and the water is crystal clear.

Any ideas about what to do to conquer the GSA problem in the 180? It'd sure make life easier to put the dumb scraper away.


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## MatPat (Mar 22, 2004)

I have found that keeping higher levels of PO4 usually result in the elimination or reduction of GSA. I haven't kept up with fertilization techniques lately but it seems keeping PO4 levels in the 1.5-2ppm range (or higher) keep the GSA to a minimum. If you decide to bump up your PO4 levels, keep an eye on your NO3 as I have had mine bottom out when initially increasing the PO4


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## BryceM (Nov 6, 2005)

Yeah, I've tried that. My PO4 was up as high as 3 and still the GSA was no better. I figure if 3 ppm isn't working then going higher probably won't either.

I dunno. The GSA is the ONLY complaint that I have right now. Plant growth is as good as it has ever been so I hate to change too much.

I wonder what dosing just a touch of Excel would do....... besides being expensive, I mean.


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## MatPat (Mar 22, 2004)

I can't be of much help with the GSA as higher PO4 levels seem to work with me. 

Now, on the Excel, since you work in the medical field, you should be able to get some Gluteraldehyde fairly inexpensively. We (SWOAPE) have been using Metricide 28 for several months now and it works just as well as Excel but is about half the cost. I believe others have used Cidex with similar results. 

If the Excel (or generic version) works, we will have to somehow figure out if it was the anti-algae properties of the Excel or possibly slightly low CO2 levels that cause the GDA.


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## Brilliant (Jun 25, 2006)

Id shorten lighting duration to 9 hours knocking 1 hour off the boost. You are changing water more then I do!


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## SuRje1976 (Mar 3, 2006)

Excel spot treatment at double daily dose (NOT water change dose) with filters off for 20 minutes has eliminated GSA on my Anubias. I definitely think it's worth a shot!


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## DonaldmBoyer (Aug 18, 2005)

Dosing 2mL's per gallon of hydrogen peroxide works wonders. Dose every third day for nine days, and it will kill the GSA. So, that's a total of three treatments, Bryce......pretty sure that you would have figured that out, but you never know....  Do not change the water until after the treatment, then do a 50% water change....I would "ease up", but not stop, your fert regiment...maybe slightly decrease the AMOUNTS (20-30%-ish) during that time.

Your water will get cloudy, however.......just to forewarn you!


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## BryceM (Nov 6, 2005)

Well, there's the problem of killing it, and then there's the problem of creating conditions that don't favor it's growth. Of the two, I think the second will be the bigger issue.


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## DonaldmBoyer (Aug 18, 2005)

Well, you will need to kill it, right? 

I thought that I had read a long time ago that changing the lighting would inhibit GSA..........perhaps someone else could clarify this? Otherwise, you can increase your CO2, decrease your photoperiod, and keep your phosphorus levels up.

Sorry I can't be of any more assistance, Guaiac!


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## MatPat (Mar 22, 2004)

guaiac_boy said:


> Well, there's the problem of killing it, and then there's the problem of creating conditions that don't favor it's growth. Of the two, I think the second will be the bigger issue.


The latter will be the bigger issue since we know how to kill/remove GSA. Unless some new ideas have come up in the past 6 months or so, I believe low PO4 or CO2 levels (or a combination of both) are the cause of GSA. Adding normal doses of Excel or Gluteraldehyde (Metricide or Cidex) after cleaning the glass should let you know if the CO2 levels are in fact low. Then again, bumping up the CO2 just a bit after a glass cleaning will do the same and there will be no additional expense involved.

I supplement my CO2 injection with gluteraldehyde and notice when I quit dosing the glut, I tend to get small batches of hair algae on the sbustrate. Common sense tells me I need to increase my CO2 output slightly.

As already stated, dropping your photoperiod an hour or two may help with the GSA also. It will also slow the growth of your "weeds" too. Might be worth a try ;-)


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