Double Dosing Chemiclean

RaymondL · Oct 13, 2025

So my LFS tells me to ensure the most effective means to 100% eradicate Cyanobacteria is to double the suggested amount of Chemiclean - Ie. 2 scoops for 10 gallons instead of 1 scoop.

The reason here is to ensure a full kill and to prevent the bacteria from surviving and having build some tolerance built against Chemiclean.

Thoughts on this? I would think that the single most factor is deprivation of Oxygen, but if there's ample airstone and circulation in the tank this overdose shouldn't be a issue.

Mr. Mojo Rising · Oct 13, 2025

I've used chemiclean a few times, it works very well. I always follow the instructions carefully, I would not double the dosage in my tanks.

You have to solve the underlying problem of why cyano showed up in your tank (usually low flow and higher organics), if you don't correct the issue, the cyano will come back.

Fish Fan · Oct 13, 2025

I've used Chemi-Clean with good results a few times in the past, but many here at R2R are against its use because it's an antibiotic, and may negatively affect the beneficial biome as well as the Cyano.

Are you sure your LFS told you to double the amount of each dose, or did they possibly mean to do two rounds of Chemi-Clean? You can do a second round if needed, but I personally wouldn't double up on the dosage used at one time. Make sure you add an air stone for additional gas exchange while dosing Chemi-Clean.

Good luck!

RaymondL · Oct 14, 2025

Yeah, LFS said to double the dose...no thanks. I'll follow the directions on the box.

What happens if I exceed the 48 hours and extend it to 72 hours because I don't think I might have time to do a water change.

rayadog · Feb 3, 2026

RaymondL said:
Yeah, LFS said to double the dose...no thanks. I'll follow the directions on the box.

What happens if I exceed the 48 hours and extend it to 72 hours because I don't think I might have time to do a water change.

Did you find out what happens if you go longer? I have gone without immediate water change years ago either luckily or unluckily.