CO2 For Plants

[Lemonz]

Hi All,

I have some Questions:

1.How many bps(minimal) is suggested for a 90cm tank to sustain plant growth?
2.Heard that OHF are not advised for planted tanks with CO2 because the CO2 escapes readily, if I'm using Eheim canister filter, how should the outlet be placed such that I can minimise CO2 loss?
3.Why must CO2 be bubbled in the tank and not stored in inverted bell? Is it because the former dissolves CO2 more readily?

Thanks!

[PeterGwee]

Please kindly readup the FAQ section...it is for newbies. []

[anarchy]

i think 2-3 bps should do great. place the rain bar at least 4-5 cm below the water surface. the third one not so sure but i would advice you to get a external reactors. Internal ones are not worth it as it is slightly better than diffusers but take up much more space.

[PeterGwee]

Anarchy, using bubble rate to judge the amount of CO2 is not recommended. You would need pH and KH readings to find your exact CO2 concentration in the tank water as there are simply too many factors affecting the uptake and injection efficiency.

[CoryDorus]

Actually Q3 sounds interesting. hmmm

[PeterGwee]

Okay..a diffuser works better than an inverted bell because the CO2 is broken down into fine bubbles and the contact area is enhance, meaning more dissolve CO2....(One big bubble vs hundreds of fine bubbles..)...A reactor traps CO2 and relies on water flow to dissolve it...the amount of CO2 loss due to burping which can occur with an inverted bell is seldom found in a reactor unless the water flow is too great.

[Lemonz]

Hi again,

Let's see, from what I hear from u guys esp. Peter,
1.Placing rain-bar/outlet 4-5cm or thereabout below the water surface to minimise 'surface movements' will be better to 'preserve' the CO2 dissolved in the water.
2.The best method is to use a reactor so as to dissolve the CO2.
3.Bps is only what you see(if I use diffuser or atomiser), however, in order to understand the 'quality' of the water, better to take pH/kH readings, right?

Thank all for the replies.

[PeterGwee]

1)Some surface movement is good as it serve as a backup in case your plants are not doing very well and the O2 is low but just not alot surface turbulence though.

2)ADA produce good diffusers but clogging due to algae can be a PITA with some folks...personally, I use external reactors for its high efficiency (This one needs external canister filters to drive it though).

3)Bubble rate is useful as a guide but the key to amount of CO2 in the tank water is mainly pH and KH readings and then deriving the reading from the pH/KH table. Example..I inject 1 bubble/s currently but CO2 is only 12ppm..so I try 1.5 bubble/s to see if I can get it to 20ppm.

Guide to setting KH

Guide to setting CO2