Okay, just checking because the wood didn't look like it had been scrubbed. When I scrub it, all the BBA is gone except maybe just a tiny trace. You forgot to turn your filters off when doing the physical removal, as well. That keeps them from being clogged.
Dead algae is often easier to remove than living algae so you may want to do another physical removal this weekend since you left so much in the tank, especially the wood. Literally scrub the wood until it's all gone. Use a scrub brush and scrub every bit of the wood. That's how you'll get rid of the BBA when it's gotten so bad in the tank. Also, don't forget to turn your filter off first this time. You don't want the filters sucking up that muck.
If one water change still leaves a lot of dead algae floating in the water column, then do another water change before turning your filters back on. I find it's helpful to let the water settle a bit so the loose algae falls to the bottom, then you can vacuum it up when you do the water change. All you should end up with is cloudy water when you refill with fresh water, and then your filters should be able to clear that up quickly.
The goal is to remove 95%-99% of the algae from the wood and any hardscape that you can truly scrub. You can't scrub plants so they'll have to be chemically cleaned. That's why it's important to physically remove what you can. Otherwise, not only will you be left with too much dead algae in the tank for the bacteria to handle (creating a mini-cycle), but you can end up with too much living algae left in the tank to kill all at once with H2O2. Then what happens is you end up chasing your tail with killing it from one area while it grows back in another area. The only way to get it ALL is to reduce the total amount in the tank to begin with. Then you have a shot at hitting ALL that's left with the H2O2.
Not only watch out for a mini-cycle, but I'm concerned for your plants given the amount of H2O2 you used. Did you measure a total maximum ml amount of H2O2 to use when you sprayed it on the wood when the water was low (when you said it made the wood "smoke"). If not, then all that H2O2 ended up in the tank when you refilled it with water which could have caused an overdose of H2O2. You won't see the plants die right away. They'll die slowly. Check for stems that have turned to mush as a result of an overdose.
If you ever spray any part of the tank like that again, you have to either do it outside of the tank where you can wash off the H2O2 before putting it back in or you have to use a measured amount of H2O2 and no more. You can dose however much H2O2 you want on hardscape that's not in the tank, but you need to keep proper doses in mind any time the H2O2 will come in contact with the plants.
I hope all is going well. Please update with pics when you get a chance!
Vicki Rena Filstar pimp #142 (four XP4s/three XP2s/one XP1) Eheim pimp #301 (Pro II 2128) Victor pimp #27 (VTS-253B-320)
90g - Journal
Pelvicachromis taeniatus 'Moliwe'
75g - Journal
Pelvicachromis pulcher 'Lagos Red' Better Pics 8-24
29g - Journal
Pelvicachromis pulcher 'unknown' --
29g - Pelvicachromis taeniatus 'Moliwe'
5g - RCS colony
2.5g - Journal