I just increased the light because the alternanthera was struggling. More light seems to have helped them begin to grow again. Don't darker plants need more light to photosynthensize? Or are you saying to do this to combat the algae? Shouldn't I wait until the alternanthera is more established? I'm worried less light will result in die off.
Plants can get through period of less light. Lighting is arguably the main factor in algae growth.
Most of my plants are from South America (I think), which gets 12+ hours of sun per day. Also, the company I bought the plants from said they have lights on for 12 hours. What is the logic behind 8 hours, and wouldn't I need to cut back on my ferts and CO2 if cutting back this much on light?
Most of my ancestors are from Europe, and yet I live healthy and happily in Canada. 5 hours max per day of light to battle algae. Yes, you will need to adjust CO2 to coincide with the photoperiod. The logic is that 8 hours of light on an established tank is enough to allow plants to thrive, but not too much for algae.
I'm EI dosing and following the recommended amounts.
That's probably fine dosing wise, I've never had much luck with AR dosing EI.
You might want to look into DTPA Iron instead of the iron found in CSM+B given your pH.
Does Excel even though I have CO2 injection???
Seachem Excel is not a carbon source, it is not CO2 and it is not a CO2 replacement. Aquarium product manufactures are masters at marketing, and mislead the buyer with many products.
Excel is a mild algaecide that allows users to run slightly higher light with a reduced risk of an algae outbreak. It may or may not help break down protein films growing on plant tissue, allowing plants better access to atmospheric CO2 naturally occurring in the water.
Excel can be used to spot treat, and create plant dips to help control algae.
Excel should be used as an algaecide, not a carbon or CO2 source / supplement.
This will screw up my EI dosing regime, so once a week is how often I change water.
You can work around the EI dosing regime. Take what you dose after your normal water change, and dose it after your new water changes. Dose micro's as normal.
I think I'd rather clip off the top few inches of the plants and replant the stems for a while until the algae hopefully goes away. Thoughts on this approach?
That's fine, spot treating is only a tool in the tool box, use it if you wish or don't use it.
I'm confused (obviously), but if the goal is to regulate CO2 levels, then why is any kind of pH drop (indicative of changing CO2 levels) a good thing?
Sorry, should have said "consistency throughout the entire photoperiod is key" as plants do not use CO2 when the lights are off.
Okay. I originally had one running in 24/7 mode (sunrise to sunset with moonlight) and the second one at full intensity for 3 or 4 hours in the middle of the day until recently (when I noticed the red plants struggling). I'm afraid the red plants are going to die off if I cut the light back.
They won't die, they might lose some red colour, but if you want to algae gone, you'll have to reduce the intensity and the length of time the lights are on. The red will come right back once you've got the algae under control and can slowly begin turning the lights back up.
Also, I would just run the lights as on vs off at a certain % power, and no ramp-up or ramp-down. Some moon lights are fine if you like that look.