severe algae problem

Question
Hi, we have a 125-gallon freshwater tank with less than 15 fish, mostly gouramis, mollies and a couple of cat fish, none longer than 4 inches.  We've tried plecostamous, but they always die.  We feed them a variety of flake food 1-2 times per day and have lights on for between 8-10 hours per day, tank does not get bright or direct sunlight.  

The problem:  Water is completely bright green, you can't see the fish. Has been that way for more than 3 weeks.  We have tried replacing water in 5-10 gallon amounts, and have used algecide regularly.  The only thing it killed was some of the gourami's.  

All suggestions welcome!

Answer
Hi Rich,
Severe algae problems always are a sign that your aquarium is out of balance in something. The two main keys to fueling algae explosions are an overload of nutrients and too much light.

Likely you may have a high nitrate problem. Possibly even in your tap or source water. Doing daily water changes would definitely be helpful until its under control. If this is just a sudden occurrence than it is probably built up nutrients causing the algae bloom. I would be persistent with as large water changes as you can do everyday. Cut out the light on the tank completely for now as long as the fish can still eat and see during the day-time. Also make sure you gravel vacuum when you do the water changes, built up debris decomposes and provides nutrients for the algae. Cut back a little on the feeding too.

It will take a bit longer with a tank of this size, but with depleting the roots of the algae problem, it will go away. It may take a while though but be patient. Chemicals never do any good in my experience too.

When your tank has recovered and balanced again, make sure to keep a reasonable lighting schedule of 10-12 hrs a day of florescent. And keep up with a consistent water change schedule according to your tank's nitrate levels and stocking.  ;-)

Best of luck and I hope this helps!
Karen~