# Maracyn/gda experiment...



## Bert H (Mar 2, 2004)

Based on Scolley's results over at tpt with his gda/Maracyn treatment, I thought I'd do a little experiment of my own with Maracyn (erythromycin).

It's on one of my 50's which has a continuing minor problem with gda - day 4 or so after routine weekly maintenance, the front glass has a definite green sheen to it, and by day 7 its a little thicker. So I thought I'd use some Maracyn and see what happened.

Tank info: 50gal, 110W lighting via ahs lights/reflectors, pressurized CO2 around 30ppm via drop checker, dosed with modified EI (macros at water change weekly, micros M,W,F).

Maracyn used as follows: 4 packets day one (recommended dosage is 1 packet per 10 gallons), 3 packets for remaining 4 days. No other change to tank except for addition of Maracyn.

Results: on day 7 after my normal routine maintenance, there would be a fair amount of gda on the glass. I see none at the moment. I had left a small amount on the back and side walls, which now look a sickly green/gray.

Whether this will be long term or not, I'll know in a week or two.

But thought it was definitely interesting.

Any pharmacologists out there know if erythromycin is algaecidal?


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## Bert H (Mar 2, 2004)

Follow up: one week later. Looks good so far. There is what I would call a 'base-line' amount of stuff on the glass, about the same as I am used to seeing with my other tank. It's certainly NOT the amount I had been seeing on a weekly basis from before. I'll let you know what happens in week 2.


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## hoppycalif (Apr 7, 2005)

This is interesting! My thought is that many chemicals become toxic to different living organisms at sufficient dosages. So, the Maracyn may not be aimed at algae, but may become toxic to algae at higher doses. Just like Excel, in some ways. I have a bias against using antibiotics unless absolutely necessary, but if this is a cure for GDA my definition of necessity can become flexible.

Would the Maracyn be toxic to the fish and invertibrates at the levels that kill off GDA?


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## Bert H (Mar 2, 2004)

As described above in my useage, I saw no ill effects to any of my fish or inverts. Fish consisting of guppies, sae, otto, and catfish. Inverts are snails, rcs, and amanos.


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## orlando (Feb 14, 2007)

This is good info Bert, thanks.


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## hoppycalif (Apr 7, 2005)

Bert, my try at this isn't working at all. In two days, two doses of Maracyn, I can see nothing at all different in the GDA. Since I suspect it could only be effective against the free swimming zoospores, I plan to wipe down my tank tomorrow and dose 2X dosage of Maracyn right after.

I want this to work so bad I can taste it!


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## mikenas102 (Feb 8, 2006)

Doesn't the use of Maracyn also kill some of the beneficial nitrifying bacteria in the tank and filter? If so, the resulting ammonia spike from killing the nitrifying bacteria could potentially bring on other algae problems. Green water for example is ammonia triggered. Am I guessing right here? Yes? No?


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## hoppycalif (Apr 7, 2005)

I think this could happen, but I'm hoping the growing plants will be adequate for eliminating the ammonia quickly enough. I have been reluctant to use more than the recommended amount per gallon partly for that reason.

I'm too chicken to ever try this on a bigger tank, until it is settled that the method works, without causing other problems.


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## oregon aqua (Jan 30, 2008)

ok im a little..... well...doesnt matter....but i have been following this thread closely because i have unbelievable gda and i want this to work really really really bad.
one point im confused on is...... if gda is a algae that is a spore and you cleaned it off the glass, and it floats in the water..... why doesn't my uv sterilizer kill it? from what i understand(in my limited knowledge)
the antibiotic should kill the exact same thing as uv's except uv's should be better at it.(understand this is from the hype i have read)

i do want this to work. i hate gda and i think it is the only algae that grows when the plants are happy. good fertz.+. good light..+.. good CO2?=gda there has got to be an equation that works. dont let me down hoppy (ohhhhhhhhh the pressure does it hurt?)anda:


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## hoppycalif (Apr 7, 2005)

GDA differs from the other algae that plague us in that it has zoospores, http://en.wikipedia.org/wiki/Zoospore, which are swimming creatures. When we wipe a young colony off the glass we are pushing a lot of the zoospores out into the water where they swim around looking for a place to colonize. They soon settle back on the glass and start reproducing again. For some time I have wondered why a UV unit wouldn't kill them, knowing that would require wiping them off the glass every hour or so to keep them in the water. I still wonder about that.

GDA can be eliminated with lots of hard work, and the UV method would just be another hard work way to do it, if it works. Being lazy I want a "magic pill" that kills them while I watch NBA games on the TV.


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## oregon aqua (Jan 30, 2008)

im currently doing the black out method on my tank. i hate it!!! and im scared that my downoi or something is gonna die off. but i cant take this GDA anymore. 

i dont mind hard work to get rid of algae. but seams sometimes with algae its alot of hard work for nothing. thats why i hope this works so much i need a magic pill!


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## Peteman (May 28, 2007)

I have found UV does kill the GDA, but doesn't keep it from coming back eventually for me. In theory if the GDA likes the tank, just a few spores can repopulate the tank over time. But using UV and using those magnetic scrapers to easily get the GDA off the sides (daily) did dramatically reduce my GDA over a couple of weeks. But considering the back of the tank (87 Gal) and the corners are hard to clean I doubt I came close to getting everything and thus it repopulated.

I've come to live with it, but I guess that depends on how much you get. With good plant ferts I find I only just start noticing it after a week... which is when my weekly water change is due anyway so I just scrape it off with the mags and do a water change after. Tried blackouts but didn't work for me.

You could try UV, daily side scrapings, weekly big water changes (after a scraping) to really knock it down. Then weekly water change after a scaping might keep it down to unnoticable levels. If it eventually becomes a problem again just repeat the UV treatment.

Link to mag scraper if you haven't seen them
http://www.aquatichouse.com/Maintenance_files/MagFloat.asp

Pete.


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## oregon aqua (Jan 30, 2008)

> You could try UV, daily side scrapings, weekly big water changes (after a scraping) to really knock it down. Then weekly water change after a scaping might keep it down to unnoticable levels. If it eventually becomes a problem again just repeat the UV treatment.


that was my previous method.

if my blackout doesn't work and the maracyn doesn't pan out im going to try the let it be method. i have tried it twice but i get to a point where my body is taken over by a force that makes me clean the glass.

if that doesn't work im going to sell the fish drain the water fill it with wood and gas. set it on fire until its a black charred lump of glass and wood charcoal. then im going to put the remains in my new tank as my new hardscape.


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## hoppycalif (Apr 7, 2005)

oregon aqua said:


> that was my previous method.
> 
> if my blackout doesn't work and the maracyn doesn't pan out im going to try the let it be method. i have tried it twice but i get to a point where my body is taken over by a force that makes me clean the glass.
> 
> if that doesn't work im going to sell the fish drain the water fill it with wood and gas. set it on fire until its a black charred lump of glass and wood charcoal. then im going to put the remains in my new tank as my new hardscape.


It is always encouraging to see someone with a definite plan.


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## mikenas102 (Feb 8, 2006)

A UV will kill the zoospores that pass through it but remember these things don't only stick to the glass. You could scrape the glass til you're blue in the face however, you can't send your plants, hardscape or substrate through the UV. The zoospores live there too.


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## hoppycalif (Apr 7, 2005)

mikenas102 said:


> A UV will kill the zoospores that pass through it but remember these things don't only stick to the glass. You could scrape the glass til you're blue in the face however, you can't send your plants, hardscape or substrate through the UV. The zoospores live there too.


I agree, because when I get a really bad GDA attack, all of my plants and hardscape get covered with green fuzz at the same time, and it all seems to go away at the same time when it lives to the end of its life cycle. This may make the UV idea unworkable. Back to the magic pill.


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## Bert H (Mar 2, 2004)

Week 2 report: this one's a little bit harder to read. Towards the very bottom of the tank, it looks as if there may be a little bit more than last week, otherwise it appears as what I consider a 'baseline' amount. 

I have always seen less gda towards the top than the middle to lower section of the glass. I would think less light reaches there than towards the top, so it has never quite made sense. Any ideas out there as to why this might be?


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## hoppycalif (Apr 7, 2005)

Bert, I see that pattern too, and I think it is because more light actually hits lower down on the glass than at the top. Here are a couple of photos of a tank, right after being set up, with silty water, so you can see the beam of light and where it hits the glass (sort of). Note that very little light hits the top of the sides and ends.


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## Bert H (Mar 2, 2004)

Yeah, I guess that makes sense. And the back wall never gets much because all the plants block the light there. 

So addendum to the experiment, next week I will move one of the 2 55W lights towards the back and see if there's any effect.


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## hoppycalif (Apr 7, 2005)

Bert, what is happening with this experiment? I'm still not sure if Maracyn has an effect on GDA or not.


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## Bert H (Mar 2, 2004)

Hey Hoppy, I just replied in your thread which I just found. LOL  Anyways, what appears to be the situation is that the gda appears to be showing itself at the same level as it does in my other two tanks. Originally in this particular tank, it would start showing up 2-3 days after my water change, by day 6-7, it would be pretty thick. Now it starts to show up around day 4-5 and by day 7, it's not too bad. 

So overall, I guess it knocked it down to a more acceptable level for me. Whether in time it will revert back to the higher levels, time will tell. I have also now moved one of the lights (this tank is lit by 2 separate ahs 55W lights) more towards the back to see if that helps out as well (and I think it is). I keep meaning to do some water testing on this tank to look at NO3 and PO4 levels to see if there's any correlation with any of it, but never seem to get around to it. My gut feeling is that lighting plays a huge role in the appearance of this, in my tanks at least. Of course, that shouldn't come as any surprise. 

It may well be that low therapeutic levels of Maracyn might keep it down further, but I'm not really willing to go that route. It's a little too pricey, and I don't believe in using antibiotics in a continuous basis.


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## ranchwest (Jul 17, 2005)

I'm definitely not much of a scientist, but I certainly know that aquariums have a lot of interactivities. So, I don't think we can ever conclude that Maracyn is an algaecide based on putting Maracyn into a closed system aquarium with plants, fish, fish food, fish waste, all sorts of organisms introduced, etc. Of course, if it works many will not care about the science behind it.


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## hoppycalif (Apr 7, 2005)

Green dust algae is unique among the various algae we fight. Its spores are free swimming zoospores. That makes it at least slightly like some of the organisms that Maracyn might be effective against. It seems highly unlikely that Maracyn would kill the zoospores, but if it helps to shut down a GDA invasion I'm all for it - assuming it doesn't require continual dosing to work. I'm not sure it is understood why Excel is effective against algae either, but it is and we exploit that effectivity where we can.


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## scolley (Mar 20, 2005)

Bert - I'm sorry to hear that you did not have unqualified success with the Maracyn. As you may have noted in the two times I tried it previously, my success was now complete either. What I found was that when applied as directed, it caused the GDA to significantly reduce in the short term. Long term it was just like all other algae problems - if you don't fix the root cause, it always comes back.

I did not start out fighting GDA with Maracyn. I thought I had BGA (incorrectly, was a different algae) and I dosed Maracyn, only to find that id darn near eliminated the GDA. But only in the short term. I tried it a 2nd time with the same results. But in both occasions I had other factors going on, like fert reductions or more frequent water changes. So I never had a pure test where I only changed one things, i.e. - no change but the addition of the Maracyn.

Well I just finished a test of just that. And it was a disaster.

I began adding Maracyn daily, and made certain that there were no other changes of my routine. But I was not using the directed dose. I was using 50%. I did that because I've been wondering if a periodic prophylactic dose might keep it at bay. And hopefully a smaller dose, as that stuff is expensive. Too expensive for my 180.

I only kept it up for 5 days. On day 4 some new algaes started to appear. Some sort of green thread algae. By day 5 it was clearly spreading rapidly. So I shut down the test.

Even with the short duration and lower dose, it definitely reduced the rate at which the GDA populated my acrylic tank walls. But the conditions it created in the tank somehow made it favorable to some other algae. So I've had it with this line of algae fighting.

My personal conclusion - Taken as directed, Maracyn will (in my tank anyway) significantly reduce GDA. But the effect is temporary, Maracyn is expensive, and it appears (in some conditions) that it might actually encourage other algaes (maybe hurting the biofilter... I dunno).

Bummer. This would have been a nice fix to a bad problem.


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## hoppycalif (Apr 7, 2005)

My GDA has not returned after my Maracyn dosing (2X dose). But, I had a mild case of GDA to start with, and it ran through its life cycle before I cleaned it off the glass. So, I can't really say that the Maracyn did anything to help. Sometimes just letting the stuff finish its life cycle, wipe it off and do a water change will stop GDA. I have never before been that fortunate though.


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## Bert H (Mar 2, 2004)

Steve - sorry to hear that.  Sounds like you've got the proverbial can of worms showing itself there. I hope you can lick it, and if you do, please let us know how you did it.

Hoppy - I'm glad for your results. :thumbsup:

This is a perfect example of how there is no one way to do things in this hobby. 3 folks have tried this approach and all of us seem to have obtained different results. 

Oh, well, live and learn.


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## hoppycalif (Apr 7, 2005)

I think if we could understand how Maracyn could affect GDA we could reason out the best way to use it. My thought was that zoospores are possibly similar enough to bacteria for Maracyn to affect them, but the more mature GDA on the glass would not be affected. One of our resident biologists should do a consult here


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## Newt (Apr 1, 2004)

Does/can GDA grow on plants?


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## Bert H (Mar 2, 2004)

Newt said:


> Does/can GDA grow on plants?


Yes, to both.


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## Newt (Apr 1, 2004)

OK, how do I get rid of it?

My tank specs:
75 gal, ehiem 2028
GroLux Std and WS on 12pm to 10pm; TEK T5HO Midday 2x54W on 1pm to 9pm (I stopped the 2x54 burst - this seems to have helped)
GH5'
KH3'
pH 6.4
CO2 ~30ppm
NO3 10ppm
PO4 0.5 to 1 ppm
K 20ppm

This is the only algae I have and I am struggling with it. I've had many suggestions and all have failed. Raising PO4 seems popular but actually increases the algae on the plants. Many have said that it doesnt grow on plants just on the glass.


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