Well, got my water change water ready Saturday night, R/O corrected with pro discus mineral. Left circulating and heating overnight, normal 50ltrs I change twice a week. Yesterday morning sat looking into my tank wondering how the hell I'm gonna get on top of this bba and black hair algae?? So, over an hour spent cutting gently away trimming off all the bba I could. Long job as I have roughly 40 anubias, crypts, swords, aponagetens, ferns etc, no stem plants at all. Next, scrubbing all the leaves and stems I could get to. I can only gravel clean a 4" strip across the front of the tank, everywhere else is too densely planted, so cleaned that after scrubbing glass. Water change next. Now, that's been my ritual since I got this algael problem couple of months ago.
Have read extensively and had lots of advice on here regarding bba. Most points towards fluctuations in co2, poor flow and surface ripple. Co2 levels and surface ripple are a little at odds with each other. Last week I pushed up my co2 a little too high, discus were definitely not happy! So I turned the spray bar returning the co2 upwards for surface ripple, it had been pointing diagonally down and out flowing through plants. The fish picked up after an hour or so. That night I changed things around. I switched the spray bar to the other externals return. The now open return with my inline diffuser on was extended down midway into tank with a y piece on the end sending the flow in two different directions to distribute the very fine mist of co2. All fish fine since.
Now, after water change yday, I thought the spray bar return, only 12" long, was too short and the flow across a little too aggressive, so I added a second which has increased the length of rippling surface but its alot more gentle. I also have returns coming in from my nitrate filter and UV. These are at opposite ends and now point to the corners and downwards towards the plants, again helping movement through them. I have an eheim surface skimmer that keeps any surface films to a minimum. A small eheim circulation pump at the back 2" off the bottom ensures good movement across the rear of the tank. Safe to say, I think, circulation won't be a factor in the bba now. All that's left to do is match the co2 output to the adjusted surface movement, gradually keeping close eye on the drop checker.
I made a big decision yesterday. On my previous tank from which all fish came, I ran Purigen in the filter even tho I use r/o and do plenty of water changes. I decided when setting up this tank I was going to drop the purigen and use peat in the filter coupled with black water extract, to create a proper amazon biotope. However, opinions were mixed when I sort them as to what would benefit the fish most, so after much pondering I stuck with the purigen. I've now removed it and gone to the peat and Blackwater extract option.
Just have to see how things go then......