CO2 levels in 10g
This is my first shot at a planted tank. I worked in a LFS for a couple of years in high school, and am just getting back into the hobby.
I am trying to figure out why my plants have not been growing very vigorously and algae (brown, green hair) has taken over on the older leaves of my plants.
10g AGA, filled to the top to minimize splashing from the filter
Aquaclear 20 HoT filter, water flow set to "low"
Fluval 20 CO2 system, one bubble per second, although this varies since the "regulator" is a joke
Liquid ferts - see below
2x 18w T5 bulbs, one roseate and one 6k (3.6wpg)
Fauna - 1 betta, 6 harlequin rasboras
Skipped most of cycling by using completely established filter media in the tank (no cloudy water or any other issues). Planted the tank about 3 weeks ago. At first the piece of driftwood I had in there was leaching a lot of tannins, and it also became covered in this goopy white blobby fungus. I cleaned the driftwood thoroughly with my hands and running water, and did a 70% water change. That really helped the light levels. I was worried about light because my glossostigma was growing up instead of out, but that didn't seem possible with 3.6WPG in a 12" tall tank... or is it? Now I wonder if the water clarity was part of the issue, with all the tannins further reducing the light penetration. But I am also just seeing slow growth and increasing amounts of algae.
At first when I tested my KH I got 3 degrees and with 1 bubble/sec of CO2 I saw the pH go down to 7 or a bit below.
I just tested my KH again and I have 6 degrees - perhaps one of the rocks in my tank is buffering the pH... sigh. But I don't mind having 6 degrees KH. However the pH is now about 7.4 and that means I have 9ppm of CO2 - too low.
The thing that has changed is that the Aquaclear filter is discharging across the length of the tank (hanging on the side instead of the back). I wonder if this is causing so much surface agitation that the CO2 can't stay dissolved?
Regarding ferts, I do Seachem trace elements 2x/week. I also have phosphate and iron supplements from Seachem. I used the K and Fe once but I saw the algae really take off afterwards so I discontinued them. I still do trace elements. But I have been scared to use the K and Fe because I know if the CO2 concentration is not right I am just going to have a ton of algae on my hands.
I would really appreciate any general tips for making sure this aquarium is on track, and in particular with the CO2 levels. I am going to get a better system than this Fluval 20, quite honestly it is junk, but I have found a cheap replacement cartridge for it so I can take my time.
In particular do you all think I am losing a lot of CO2 to surface agitation?
Thank you all, I will do my best to respond promptly. I have been lurking for a while and this is really a great forum.