Would Colter’s excess food also help this black algae grow?
Yes in that it is more organics entering the system, but on its own not significantly, but you want organics at a minimum. When fish sdpit out food, it is not necessarily because they are not eating it; they may take off little bits and spit out the rest, and continue doing this. So I would reduce feeding.
The fertilizer I use, that was recommended by a Betta person is aquarium co-op Easy Green. Now, I will add it after water changes. I was doing it in between.
I looked this up and it has most of the nutrients that are needed, so this should be OK. You might want to reduce the amount you use though; excess fertilizer means algae, just keep an eye on the plants to ensure they are still doing well.
Use fertilizer the day following the water change; this is suggested because most conditioners detoxify heavy metals, and these include some nutrients (iron, copper, zinc, manganese come to mind) so there is no point in detoxifying what you are adding. A minor point, but one suggested to me by Seachem a couple years back and now that I have been doing it there was no detriment so seems OK.
When you do a water change, you are usually increasing the CO2 as there can be CO2 dissolved in tap water; those are the tiny bubbles you see. I have even had plants pearling (releasing so much oxygen because of photosynthesis) for a few hours following water changes due to the increase of CO2 driving photosynthesis faster. So adding fert the day following is getting it to the plants quicker.
The tank has two sponge filters. I have not rinsed them out because I read you shouldn’t remove the good bacteria. Wow! I’ve really screwed up....
Bacteria live on surfaces, and being very sticky it is not that easy to dislodge them. I rinse my sponge filters under the tap at every water change. You don't need to worry about chlorine; for one thing if chlorine only is added to your water it is likely it would not kill these bacteria anyway (chloramine is a different story) but even if it does, there are more bacteria in the substrate than the filter, plus the plants. Keeping filters free of organics is important in my view.
I do partial water changes every week to 10 days, they are due, but never that much, I usually do about 30% water change, obviously not enough!
I’m really bad at siphoning the substrate I have not been able to do this properly. I also think I might have too many plants, cholla wood in the tank. I have such a difficult time siphoning. I seem to make a mess and not suck up the debris. Incredibly frustrating.
Increase water change volume to half the tank or so, that's OK. You really cannot change too much water, provided the parameters (GH, pH and temp) are reasonably similar, and the more water changed the more stable these will be so a double benefit.
I don't dig into the substrate around plants or under any wood or rock, just open areas; in some tanks I don't even do this, and I have sand. It is only one factor in organics, but plants need these, so I wouldn't worry.
My light is on a timer. I was going to go manual, because it has a nighttime light, which I’d prefer to wake them up with and also put to sleep with, instead of big light jolts. They are in my bedroom which is pretty dark. But I’ll keep on the timer as you suggest and remember to change nighttime light before going to sleep etc. Hope that makes sense.
Yes. There must be ambient room light when the fish tank light comes on, and when it goes off. This can be diffused daylight or a lamp. The light should remain for say 40-50 minutes after the tank light goes off. Sudden bright light on/off will seriously stress fish.
