# A story of 2 tanks - thoughts welcome...



## Bert H (Mar 2, 2004)

I have 2 - 50's. One's an Oceanic 50 the other is an AGA 50. The Oceanic measures 30 inches wide, while the AGA is 36 inches wide. Both are pressurized CO2 around 30+ppm measured via drop checker. Both have a flourite/Eco substrate mixture. Both have the same fish load, more or less. Both have the same clean-up crews, fishwise. Both are dosed exactly alike. 

The AGA is lit via a 96W (6700K) ahs kit strip plus a 30W strip for a total of 126W of lighting, photoperiod of 10 hrs. The Oceanic is lit by 2 - 55W ahs retrofits, one of the bulbs being 6700K the other 9235K for a total of 110W lighting, photoperiod of 9hrs. 

The AGA tank runs smooth as a race car engine (hope I'm not jinxing myself by saying this). The Oceanic keeps having on and off issues with gda. Other than the different spectrum of lighting, I can't figure this one out. I have cut the photoperiod to see if it helps, but it doesn't really seem to matter. I have used the 'don't touch it' method for a month, it goes away for a little while, but then starts to come back. 

Does anyone have any thoughts or ideas they can offer?


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## BryceM (Nov 6, 2005)

The Oceanic tank is taller with less light? What types of plants are you trying to keep in it? How densely is it planted. IMO 110W isn't that much for a 50g tank, especially if it's tall. Are the stem plants dropping their leaves near the substrate? Under certain circumstances, I think too little light can lead to algae issues if it isn't sufficient to allow for optimal plant health and growth. Anything that leads to unhappy plants can give algae a chance to grow.

Other things to consider - are the tanks the same age? New tanks will have more issues. Are the bulbs old in the one you're having issues with? Is one tank sparsely planted with anubias and mosses while the other is loaded with stemmies? That could lead to big nutrient availability issues.

Now, just a caution to everyone else. I'd say that 95% of the time, algae issues are due to too much light, not too little. I happen to know that Bert is probably on top of everything when it comes to CO2 and ferts. GDA algae is a huge PITA though. It's sometimes hard to figure out, and then one day it magically goes away (or not ). I've got it bad in my 180g right now. All the plants are growing well so I've just resigned myself to a weekly glass-scraping. I'm even running UV 24/7 - on or off it doesn't seem to make much difference. It isn't that big of a deal and as long as everything else is going well, why get worked up over it?

IMO, GDA should stand for @#% &*@# algae,not Green Dust Algae.


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## hoppycalif (Apr 7, 2005)

I haven't seen any convincing information about what causes GDA in the first place. I assume that our tanks all have those spores present in a dormant state, but for some reason the #$%#*@ Algae starts to grow. I wish one of our scientist type members could find out what causes that to happen. I have had it, and still live with it, with light intensities of 3.8, 2.4 and 1.6 watts per gallon. The only difference I see with light intensity is how fast it restarts and how thick it grows. My last effort to get rid of it was a one month period of letting it grow thru its life cycle. But, it's still there a week after wiping it all off, very carefully. To me this is an enduring mystery algae.


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## Bert H (Mar 2, 2004)

Yes, the Oceanic is taller with less light, BUT... plants requiring more light seem to do better there than on the AGA. Examples: L. aromatica and P. palustris look real nice on the Oceanic, but look puny on the AGA. The aromatica does lose its lower leaves after a while, which I've learned to live with. Except for those two stems, the rest of the Oceanic is Crypts, Anubias and Blyxa. The AGA has more stems than the Oceanic.

Both tanks are well established, the Oceanic being 15 months old MOL. As far as bulb age, the AGA has bulbs that are a year older than the Oceanic.  



> All the plants are growing well so I've just resigned myself to a weekly glass-scraping.


I have basically resigned myself to the same thing. I have to say of algaes to have, this is one I can live with. But still, a certain level of frustration exists...


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