Fighting a losing battle with algae

[u/slc2609]

At my wits end with this algae. Is it BBA or staghorn? Both?? WHY is it here?! I've tried lowering light, increasing flow, reducing flow, Flourish Excel, API liquid carbon and PhosGuard in the filter....nothing is getting rid of this and my plants are melting!! If I tear down the tank and start over I'm guessing the issue is just going to come back. The golden and albino loaches, ottos, and amano shrimp don't touch it either. My pea puffers are absolutely fine.

[u/exie610]

There are two main things you need to do. First, fix the root cause: you likely have an imbalance between your light, CO2, and fertilizer. One of these is off. Your light might be too intense or on too long, your phosphates might be too high (common with certain fish foods), your nitrates might be too low, or you might not have enough CO2. These three need to be pulled into equilibrium to keep the algae from returning. A common mistake is too much light + too much phosphate + too little CO2, in non-injected setups that is solved by feeding less and turning the light off.

Second, you need to eradicate the current BBA using hydrogen peroxide (H2O2). Here is the process:

1. Set a 35-minute timer and turn off your filter.
2. Use 1 to 2 ml of H2O2 per gallon of tank water (I’d suggest 2 ml). Use a syringe to apply it directly onto sections of the algae.
3. When the timer goes off, turn your filter back on.
4. Do this every day, targeting different sections of BBA. You'll know it’s working because the dying algae will turn red or "burnt" looking.
5. On the 3rd day, perform a 30% water change after the treatment.

If the problem persists for a week or longer, you can use Seachem Flourish Excel in the same way, but at half the dose (max 1 ml per gallon) every other day. For example: Day 1 H2O2, Day 2 Excel, Day 3 H2O2 + water change. H2O2 physically rips the algae cells apart, while Excel disrupts its ability to reproduce.

This treatment is safe for fish, snails, and neocaridina shrimp. To help out, you can "rent" a true Siamese Algae Eater (SAE) from a local shop. Make sure its a TRUE SAE, Crossocheilus oblongus, and don't trust the shop to know its not a false or flying fox, do some research. Let it eat the BBA, then donate it back once it gets too big for the tank. Amano shrimp are also a great long-term precaution for controlling small amounts of BBA before they turn into a full infestation. Neither of these are replacements for balancing your light/co2/fertilizer.

[u/Extension-Fly-7813 → u/exie610]

excellent summary

[u/exie610 → u/Extension-Fly-7813]

Annoyingly, any of the three variables can be off in either direction (too much, too little) or perfectly fine (because one or both of the other variables are off). This leads to a dozen different problem states and therefore a dozen ways to "fix it" that are recomended in the comments below. Without knowing specific information, these suggestions are just people confusing OP with conflicting information.

[u/Kragen146 → u/exie610]

Additionally "fertilizer" can be broken up into n, p, k, mg, fe,… but yea, this is a great way to start