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Hi Dennis,

Sorry that the algae has hit your tank so badly. Tom Barr hopefully will chime in if he has the time.

He recommends dosing 10 ppm NO3 twice per week. With 50 % WCs, that means a maximum concentration of NO3 of 40 ppm if the plants aren't taking any in. You seem to be limiting your NO3 to 10 ppm or less.

Tom usually recommends 5 ml flourish per 20 gallons. That would mean 2.5 ml of flourish for your tank (twice per week). This single dose gives about .23 ppm. Current thnking is that 1 to 2 ppm Fe is better. So I would aim for 1 ppm Fe twice per week (12.5 ml Flourish twice per week).

PO4 shoud be between 1 to 2 ppm, twice per week.

And all these nutrients are to discourage algae!

Most important is your CO2. Are you checking your pH and KH to determine your CO2? Keep it between 20 and 30 ppm. If your DIY CO2 is not reliable, use a cylinder. All the dosing should be consistent.

Test kits (except for the CO2 determination) should not be used to figure out how much of a nutrient to add to a tank. T. B.'s estimative Index (is that what it is called?) is set up so you just add the nutrients on a schedule and the water change prevents overdosing. It is far better to have more than enough of a nutrient, than not enough.

You will be far better off if you get into a good schedule of dosing and put all your test kits away (except for pH and KH). Test kits should not be blindly trusted.

Sorry for the long discourse. It took me years to get all this down right. Tom Barr is right but you must follow his recommendations completely for them to work. Also sorry I can't help with the algae problem. I think Tom Barr recommends some reduction in nutrients as well as the blackout. I would not do the blackout until you have all the details, so you have the best chance of success. It might be good to search the APD archives for "Blackout". Also Tom usually recommends to remove as much algae and decayed organic matter as possible before a water change. He feels good hygiene helps. Generally, I find that all these nutrients do not promote the growth of algae, but you have to remove what is there by trimming, etc.

Good luck.

Steve Pituch
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