[Dale]

Hello,
I have a 30gal and 35 gal tank. Both have the same plants, I dose the same fertilizers and amounts, DIY co2, 50% weekly water changes (Barr Method). The only differences are the 30 gal has a fine gravel bottom and 2wpg and the 35gal has fluorite and 2.6 wpg, sometimes 1.7wpg since I leave one of the lights off.
The 30 gal is algae fee and has been for 2 or 3 years. The 35 gal has constant algae problems. The swords in the 35 gal tank have dark patches on the leaves that smells like BGA but does look the same as a previous outbreak of BGA I had about a year ago. The patches, if rubbed will leave a dark residue on your fingers.The swords also have an algae that has the look and feel of velvet.
Am I dealing with BGA or something else. Any reason why one tank has problems and the other tank doesn't?
Thanks for any suggestions.
Dale

 

[Dale]

I have 2 bottles of DIY CO2 on the 35gal. tank and only 1 on the 30gal. tank. All 3 are due for a change and I will do it this weekend.
I changed 50% of the water in the 35 gal tank on Wednesday and my NO3 was around 20ppm before the change and 10ppm+ after the change. I did not dose KNO3 since I thought it was getting too high. Should I add more to get it back up to 20?
My K is dosed to get 20ppm, PO4 .6ppm and Fe .1ppm, PH 6.6-6.8 and CO2 usually 20ppm sometimes higher. Like I said before, the 30 gal has been no problem, the 35 always has algae problems.
Thanks for your help.
Dale