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Non co2 algae help


Community Member
Jul 19, 2023
Reaction score
I havent yet figured out how to keep a low tech, ie non co2 injected planted tank as algae free as I would like..

I may have struggled 6 months or so on my main tanks before I invested in co2 for them. The CO2 had an immediate impact when I added it but it wasnt the cure all…. Adding a canister filter with spray bar and various horticultural tips from the 2 hr Aquarist helped me bring the display tanks to the condition I wanted….

Well, I was curious to try another non co2 tank to see how much of an impact the improved housekeeping tips from the 2 hr Aquarist would get.

So I started a 17 gallon spherical bowl, home made ugf plate with Aquarium Co op Easy Flow kit on it. SafeT Sorb substrate with pockets of aquasoil, capped with BDBS. I also have an 80 gph power head , dialed down a bit with an intake restrictor to increase flow.

I do weekly 50% water changes keeping the parameters stable. Dose with Easy Green to around 20 ppm, gh 4 degrees kh 1 degree, Iuse a turkey baster to move detritus up into the water column and hoover that cloud up with a gravel vac as it is suspended and manually remove algae as much as possible.

Mostly easy plants, anubias, Java Fern, Bacopa, Ludwigia Repens, red Wendeti crypt, pink Flamingo crypt, S Repens, hornwort, water lettuce rounds out the plants…

A familiar nemesis from prior attempts shows its face…. A thin fairly strong filament type algae and some hair algae…

The Crypts melted back and I am seeing good new growth and the Java Fern shot out all sorts of baby plants that are growing well. The Ludwigia grows ever so much slower without CO2 but looks healthy and is algae free. The crypts have a bit of hair algae. The Anubias looks decent…

This tank is roughly 3 months old.


So, any recommendations? Stay the course and be patient for tank to mature? Or make changes?
I have a Finnex ALC running 100% red, 50% green, 30% blue and 40% white. It is controlled byan inline Nicrew timer that brightens and dims over 15 minutes so I dont need to use the worthless onboard timer.

Two photoperiods from 4:00 to 8:00 AM and PM.
I'll offer my two cents, focus on the plant health as leading indicator and as a result algae will get in check.

I've been struggling with plant health and no idea what else I could check or do, until I discovered my photoperiod was not long enough (6 hours). So I like @Chris Moon question, and would check what a regular 8-10 hr photoperiod would do for your plants.
Mostly the plants seem to be doing well. I have 1 crypt that has 1 leaf that has a few strands. Other than that I see some on anubias roots, but the leaves are fine and also som e of the Java fern plantlet roots.. the Java Fern leaves are fine…. And some growing on a rock or two. I pull that out and clean it with peroxide and replace…

In my Co2 tanks I never see it anymore…
I would completely remove the split photoperiod. Im thinking 20ppm is a bit much for this tank. Right now you dont have much plant mass to eat up all those nutrients. WATER CHANGE, WATER CHANGE, WATER CHANGE. Even if its 2x or 3x a week. Get in there and clean and scrub every single inch.
Tonight I pulled out all rocks, driftwood anubias, java fern. Spent some quality time with siphon and turkey baster to suspend detritus and hoover it up..

For the time being I am going to stay with the split photoperiod as it matches my other tanks and fits my lifestyle much better, but I will keep the thought of altering in the back of my mind for later as needed.

I lowered fert to nitrate dosing of 15 ppm from 20.

I will continue with twice a week cleaning, water change for a month and see what it looks like.
I followed up with another whole bowl cleaning session removing rocks, driftwood, annubias, java fern, and installing a Lee’s triple flow box filter in the back with gravel in the base to weigh it down and polyfill on top. The mid size Lees will allow an Aquarium Co op Easy flow kit air collar to friction fit to the top. The goal was strictly mechanical filtration help. The easy flow kit significantly increases flow through the filter. Within 20 minutes of running there was significant brown staining to the polyfill on all three intake corners.

After restoring all hardscape and plants in the tank, I followed a 1-2 protocol of whole tank treatment with peroxide followed by gluteraldehyde I read about on a planted tank forum. It involves stopping filter flow to preserve beneficial bacteria, and a double normal dosage of peroxide with high tank circulation. I fitted 2 80 gph power heads and added 90 ml of peroxide and let it run for 15 minutes and then did a deep water change to reduce peroxide levels. I then followed up with 8 ML of gluteraldehyde in the tank and left powerheads running and turned fikters back on and left it overnight. The following morning I did another deep waterchange to reduce gluteraldehyde levels significantly. The theory is that the high peroxide for 15 minutes seriously weakens the algae while the short time period is tolerated well by livestock. A single loading dose of gluteraldehyde effectively kills off weakened algae.

I am at day 4 of no visible algae in the tank and will continue with box filter mechanical filtration and more frequent waterchanges and see how it goes.

The livestock seem unaffected by the treatment, but I would prefer to not need to repeat it often. My preference is to prevent recurrence by non chemical means.
Watch the livestock like a hawk. The 1-2 punch algae treatment nukes your biological load totally. Your tank will cycle again. Best bet do daily 65% water changes. Edit: If youve got media from another tank dump it into the new tank.
The 1-2 punch algae treatment nukes your biological load totally. Your tank will cycle again.
That thought occurred to me. I have been testing ammonia and nitrite morning and night since water changing out the Gluteraldehyde 14 hour after dosing it.

It has been 3 days since that water change and I remain at 0 ammonia, 0 Nitrite.

I had shut off the air pump while the peroxide was in the tank, so possibly that saved the beneficial bacteria in the Under Gravel Filter.

I plan to continue daily testing for the rest of the week.
Well, he tank has been free of visible algae now for over a month.

I had been starting to doubt I would ever get to that point in a non co2 injected tank.

It is rather startling how much slower plants grow in a non injected tank…