Question About Water Changes / Bba In My Low Tech Tanks


Junior Poster
Feb 10, 2015
I currently have 2 low tech tanks set up. Both have small amounts of BBA that I have been dealing with for awhile. Both are pretty heavily planted with the plants listed

20 gallon long:
finnex stingray w/ 1 piece of window screen and glass top / photo period 6 hours
fauna: crypts, anubias, marsilea
bi weekly water change of 15-20%
once a week ei dose / aquasoil

20 Gallon High:
Finnex planted plus w/ 2 pieces of window screen / photo period 6 hours
fauna: ferns, vals, dwarf sag, crypts, Aponogeton Boivinianus, anubias, tiger lotus
bi weekly water change of 15-20%
once a week ei dose / aquasoil

It seems I have tried everything over the course of several months including: reducing light / photo period, weekly ei dosing, off gasing water for 2 days before water change, cleaning filters, spot dosing excel, and reducing blocking light that enters the room from windows. It seems that the BBA always returns in small amounts.

My question is are my plants likely too slow growing for bi weekly water changes or is there another cause? The BBA usually targets marsilea, crypt parva, ferns, anubias, and the aponogeton. I assume im at around 15-30 par based on par ratings for the lights. Nitrates stay at around 5-10 after 2 weeks.

I can add more info in comments so it's not a wall of text.
Last edited:


New Member
Sep 10, 2018
Hi Mexicatz,

..this forum is so quiet..

Have you read the sticky on non c02 methods?

I'm an amateur when it comes to dealing with planted tanks so my advice is only based on what I've read recently. I'm having probably my 5th go at trying to keep my small tank algae free and so far it seems to be going a lot better than previously. I'm taking on board all of the advice from the sticky mentioned.
Algae is normal, algae blooms however, from my research (and info within the sticky), are caused by;
  • Fluctuations in CO2 levels (algae adjusts to cope with fluctuations much more quickly than plants)
  • Excess light
  • Poor plant health
  • Low plant mass
  • Ammonia spikes
  • Excess organic ferts
What does not cause algae blooms are inorganic ferts and inorganic ferts are essential for healthy plants which are essential for keeping algae at bay.
I would question the need for doing so many water changes as from my research this causes CO2 fluctuations which causes algae to grow.

Make sure you are dosing enough macro and micro so that the plants are never limited in their requirements as this will keep them healthy, and I'd drastically reduce water changes.
Try adding algae eaters. SAE, shrimp, snails etc

Just my two cents


Article Editor
Staff member
Lifetime Member
Article Editor
Sep 16, 2015
Hillsboro, OR
Low tech tanks witnwith relatively slow growing plants is harder.
In low tech tanks you do not want to do too many WC, the aim should be to provide stable environment, top offs and do occasional, WC when you see water become very yellow or the TDS ceeeps up a lot.
If BBA is on older growth, it’s not uncommon in low tech tanks. I usually remove that leaf. If it’s spreading much more than that, I spot treat it with H2O2 and also do a large WC then monitor again.