This is a long thread below, sorry for all the explanations but might help understanding what's happening to this tank.
The green chlorosis was actually on the newer leaves. I didn't bother taking pictures as it was gross but found one that shows it a bit. It's from beginning of December. The plants were gone totally wrong, green spot algae, brown tips on the amazon swords and aponogeton, green chlorosis, etc.. A batch of amazon frogbit and salvinia minima had already miserably died after struggling for a month but flourished in another tank so I had a chance to try again middle of December. I wanted to use it to block light because I thought it would help with the GSA.
Below is a recent pictured history of the tank.
Beginning of December 2012. EI dosing. No floating plants survived. Surface clear.
Here next to the pleco's nose you can see the green veins in the anubias nana. All anubias were somewhat like it but it was the new leaves rather than the old ones. The old leaves of amazon swords and aponogeton had brown tips here and there as in the picture below(the left thin leaf is amazon sword)
Around the 1st-2nd of December 2012.
New leaves get attacked by GSA in no time, starting like this:
And then getting like this:
About the 9th of December this tank still has no surviving floaters but the ones in the other tank started dying as well so I decided to transfer some to save them and give them a chance here again. I put salvinia minima and amazon frogbit. They started multiplying rapidly for the next 3-4 weeks.
Here it's the salvinia minima mostly flourishing. Pic taken on the 6th of January 2013
After this picture, the salvinia minima went downhill. Still full EI dose at this stage.
So I decided to bin 23rd of January but unfortunately no picture taken with it with the holes. However, the amazon frogbit was still ok. At this stage the 2nd tank I got the floating plants from to reload this one, had no surviving floaters. I put two small salvinia minima survivors in a 3rd tank(betta small tank) and it has multiplied since and still doing ok there.
Here is a picture from the 23rd of January just after I binned the salvinia.
I was still battling the GSA and then I read an interview with Amano Takashi on GSA. Surprisingly he said excessive nutritients(although every one claims there's no such a thing), higher temperatures(my tank falls within the ones he said), lack of water changes(that wasn't the issue as I'd done a lot and big) all lead to GSA. So from these three factors, temperature wasn't changeable, water changes were done, I was left to cutting down the nutritient dosage after trying overdosing on all to stop it, particularly fosfo, nitro and potassium. I did two major water changes and started dosing lean(just a bit over PMDD) I cut out the nitrAtes and fosfo. I know the nitrAte test is unreliable but between 4 tanks, this one was off the scale before the big water changes and PMDD. TDS used to creep up during EI regardless of water changes. The tank is well stocked(big pleco and 5 clown loaches and lots of small fish)
4-5 weeks after cutting the doses but keeping the rest of the factors, same amount of light and carbon, inclusive of 50% water changes) I got improvements on the GSA. The anubias started flowering and no green spot algae on 4 new leaves, one is at the back. Same effect on the other anubias, growing darker bigger healhty leaves and leaves don't develop GSA anymore.
So when I think of it, possibly I've got N, P, K and even magnesium defficiency but I am still dosing potassium, micros and extra iron, but maybe not enough potassium because I've cut down. However, the pattern of dying floaters is in more than one tank, twice on this one, once with EI and once with PMDD. They first died when I did EI, after a month struggling, then on the 2nd attempt just the salvinia died when still EI, then whether coincidental or not, the amazon frogbit did die when no N and P added to the tank but the rest of the plants had a massive improvement during this time unlike the amazon frogbit. Generally, the pattern for floaters is a month and a half of thriving as in taking excessive nutritients, then going downhill in the space of week or two when done the job.
On a side note, my other tanks aren't dosed with nutritients or CO2 and do not have any visible algae. They do get the occassional nutritient deficiency which I try to correct the way I know but no algae. However, I've no idea what's happening to the floaters. Maybe it is bugs after all
So the plan is now to dose N and K(what ppm do you recommend?) and get magnesium as I've never tried extra of it. I just want to be careful because I just won't cope with another GSA outbreak.
