I currently have 2 20 gallon tanks set up with 125 Watts of light on each.

I put the same types of plants in each.

One tank is CO2 dosed in large quantities.
Also dosed are Seachem Flourish
Potassium Sulphate once a week with water change
KN03 and KH2PO4 every second day
Seachem Flourish every second day.


One tank is a "Diana Walstad" tank.
About once a week I dose the same things I'm dosing in the CO2 tank.

After 3 months of observaions I have noticed:
Water in the CO2 tank is crystal clear, while the "Diana" tank is slightly darker.
After a few days water was green in the Diana tank, but cleared up after a coule days. This didn't happen in the CO2 tank.

Plant growth has been close to progressing at the same speed.
Algae growth in both tanks has been minimal, but there is a development of a type of branchy algae growing on the slower growing plants in the Diana tank.

From experience, I know that the "Diana" tank will not hold in for the long term. I expect it to start slowing down in the next 3 months.


Cost of the Dianna Walstead tank. $125.00 including the lighting.
Cost of the CO2 tank (complete with pH controller) $1200.00.