2 Month Old Tank Algae Bloom


New Member
Apr 29, 2021
Indiana, USA
Hello Everyone!
I will start out by saying I am new to the hobby still, and am still learning. I read a lot and have gained a lot of information so far, but I still got an algae bloom and it continues to come back.
My set up:
ADA 90p tank
Oase biomaster 600 thermo with Seachem Matrix media
ADA Vuppa II skimmer (Also have Skim 350)
In tank co2 diffuser (turns on two hours before light)
Twinstar 900sm III light (8 hours per day)
I dose 2hr Aquarist APT EI (4ml/day)
ADA Amazonia V2 soil (pre cycled the soil for a month before planting)

I do NOT use RO water, and I do 40% water change twice a week. (Tuesday and Friday)
Any help is greatly appreciated!





Feb 24, 2019
Modesto, CA
My thoughts...

Is that seiryu stone? What's your Gh?

What's your pH drop? From completely degassed tank water.

It doesn't look horrible so you are probably just off by a bit, especially with the amount of stems you have in the tank.

The easiest solution would be to lower your light duration. I'm at 5 hrs 100% intensity right now up from a low of 3 hrs last year.

CO2 will be the toughest to figure out, especially if you don't monitor pH with a ph monitor. Drop checkers are great but have lag time and a resolution problem. Not that the pH drop is perfect. It has its own set of issues. :)

I also wonder about your water changes? 40% 2x per week seems like a lot but it really isn't. It's not the same as one 80% 1x per week. Nutrient buildup will be higher in a tank doing multiple smaller water changes than one massive one. Most of the aquascapers I follow online do multiple 70-80% water changes per week when they are dealing with an algae issue. They also bump up the co2 to the max possible.

As to Ferts, I wonder if the added nitrates from APT EI are causing issues? I realize that nitrates from Ferts are drastically different than nitrates from fish waste, organics breakdown, but elevated levels, made even higher by your young substrate, aren't going to help get rid of an algae bloom. And then there is phosphate. Active substrates have a tendency to pull nutrients. All tanks are different with this but you may need a bump up in water column phosphates? If you could measure that would be great. I've seen nice tanks running with as high as 10ppm. Not that I recommend going that high, lol! But even if you are in the 2-6pppm zone it might be worthwhile bumping it up a tad and seeing what happens?

After all that said, it will more than likely just clear up as the substrate matures. :)

Here's my 10gal co2 tank right before a trim this week that gets 5hrs of 100% intensity light. I'm about ready to bump that down to 3 or 4 due to an hr of direct sunlight that hits the tank during summer months. While I battle beard and silk algae I can go 2 weeks without wiping the glass even with the hr of direct sunlight. First 3 months of this tank, not so much.


Sent from my Pixel 3 XL using Tapatalk


Super Moderator
Staff member
Lifetime Member
Jun 20, 2016
Looks like its time to get the clean toothbrush and exert some anthropocentric ecological pressure on those algae ;) after you get rid of the bulk of it, weekly cleaning of the rocks and a shrimp crew will probably be enough.