New tank, new light, and now green water

finsNfur

AC Members
May 29, 2008
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I upgraded my 10 gallon tank to a 20L a few weeks ago, and used the old filter/gravel etc. to help cycle the tank faster. It has a new Nova Extreme 48w strip light across the top. I have some java fern, java moss, anubia, amazon sword, and a very small amount of water sprite in the tank. I also have a few guppies and platies in it, and an apple snail. The water turned green within a few days after setting up the tank. Some of the plants actually look like they have green algae spots growing on them now. I've been running the lights about 12 hours a day, but the past few days I've cut that down to about 8 hours a day. I'm doing 20% water changes every day or two. Am I doomed to green water in this tank because of the higher wattage? I've just had terrible luck growing plants with the typical lighting that you get in kits, and was really excited to buy something with higher wattage. Now I'm afraid maybe I shouldn't have spent the extra $$ on lighting. Is there something else I can do to get rid of the green water? Or might it go away in time, since this is mostly a new tank? The tank doesn't get direct sunlight. I once battled green water in another tank that was getting direct sunlight, and even after moving it, it took months to get rid of. I am getting increasingly nervous here; I'm not a fan of green water.
 
I think you're right, but the move probably contributed as well. The plants might have had a little moving shock, and green water can occur with small ammonia spikes, again probably from the move.

To help curb it, I would run 1 bulb no more than 8-9 hrs, 48watt of T5HO is too much for a 20L with lower light plants and no Co2 addition. You can try a blackout for a few days, or if you have the money, there are inexpensive UV units you can try, which will guarantee the end of green water.
 
Oh no, not what I wanted to hear. I had a thought, I have a 20w strip light on my 29g tank, which is ridiculously low. Maybe I can just switch lights and put the 48w on the 29g tank, and the 20w on the 20L tank? I just do not want to deal with CO2 etc. I just want to be able to effectively grow water sprite and hornwort without them falling apart. Maybe switching would work better. Thanks for the advice!
 
That would be a good idea. It would put both tanks in a medium light bracket. If you don't want to mess with co2 that is what you should do.
 
Thanks! I was talking to someone today about it, and he suggested it could also be the liquid fertilizer I added to the 20L when I first set it up, too. At any rate I switched the lights on both tanks. He also gave me some more water sprite, which I have floating at the top. I'll look into getting some water lettuce or frogbit. I've had both before with less light, and had no luck with them, but maybe with more light they'll do better.
 
A uv would clear it in a day, a magnum 350 with a micron filter with diaton powder would rid it quickly also. It would just cost you some bucks but it's not something you would need to run all the time but have around if you ever need now and then.
I have use both methods with 100 % results.But I only had a serious green water one time.
 
Had the Green water problem in the winter time, after I cleaned the filters, tried everything, UV filter from Petsmart did the job 3 days. $50
The free solution in the summer would be to get willow tree branches and see if that will work for you. That is what was used in the old days!
good luck
 
I have a newbie question, is it okay to use blue light for my tank or just use a transparent one?
 
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