Balancing Co2 and O2

[bibitte]

I have 120g tank with a dozen Discus juvies. Some growing Amazonian swords, vallisneria and anubias from trims but nothing overwhelming. I have added root tab so I don't put ferts in the water column. I have been thinking about Co2 injection. How do you guys balance between Co2 injection and O2 air pump? The air pump cancels the injection and I am afraid I'll kill the fish with too much Co2 (especially while I am at work.)

Your advices?

Jack

[pcsb23]

Hi Jack,

First off you have nothing in the tank that requires CO2 injection so it may be a moot point. The swords and val will grow faster with CO2 but they will still grow acceptably without.

It is a common misconception that adding CO2 depletes O2, it doesn't. But you are correct too much CO2 will kill the fish.

In high tech planted tanks we still try and get some surface agitation, even though some CO2 will gas off. And once you start to add CO2 it is classed as high tech ;) I don't run airpumps on planted tanks, I generally aim the output from the filter at the surface and if I'm using a supplemental powerhead that too is pointed at the water surface. Just enough to cause some rippling is fine.

If you are going to add CO2 I'd strongly advise getting a solenoid and a timer, have the CO2 come on about two hours before lights on and go off two hours before lights out - I control my lights and CO2 on timers. Also make sure that the regulator you are using is decent quality and can easily be adjusted. Consistency is key with CO2.

There are a number of ways at working out how CO2 you are putting in, but for such a few plants I'd not even try and get near the so called maximum. Honestly in a tank with a few swords, some val and annubias I wouldn't bother with CO2.

Also if you do add CO2 you are likely to need to add water column ferts too, root tabs are ok as far as they go, and for how it is set now is fine, but once you start injecting the plants will need more than root tabs can give.

Another option would be to use something like excel or easycarbo - these are liquid carbon supplements. If you used a smallish amount of this twice a week or so it will help with the plants and may avoid the need for a lot of expense, time, energy etc ...

[bibitte]

Thanks for the reply Paul.

Too late. :D I ordered a CO2 controller and had some dry fert and CO2 bottle from my previous 26 gal. setup which was my experimentation with high tech tank. It's just that now with my 120 gal. Discus tank, I am somewhat reluctant to experiment and make sure that I know what I am doing before I plug in the regulator.

You mentioned that the type of plants I have did not need CO2. What plants do you consider CO2 Discus tank worthy?

With the frequent water change, how do you keep up the fert in the water column? What's your weekly schedule for your tank up keep?

Jack

[pcsb23]

Plant choice can be quite personal, it really depends on what you want. Many folk are happy with a few healthy plants to set-off the discus. Some like densely planted tanks ... but my preference for a non native type tank would include a variety of swords such as e. Red Diamond and e. Tenellus, as well as the easier to keep e. Barthii and e. Ozelot. If you want some stem plants then depending on lighting many of the Hygrophilia are nice as are ludwigia and Pogostemon. Once you are using CO2 then it definitely opens up plant choice.

Most people who go injected CO2 try to run this at the so called max safe limit of 30ppm, I don't advise that with discus as the fish will develop a matte colour, be darker and generally exhibit low level stress signs, their eyes will also cloud. You are at an advantage in one sense with a larger tank, it is harder to overdose CO2 in these tanks! Consistency is key with CO2, set your regulator to deliver somewhere between 3 and 5 bubbles per second and you should be fine in your 120.

With planted tanks my advice is to stock at lighter levels than you would a bare tank and stock with adult or sub adult discus. Then do two or three water changes per week.

In larger tanks it makes sense to use dry ferts, liquid ones are just too expensive!. I dose every day in my current tank simply because I'd forget otherwise! I have the CO2 on a timer as well as my lights on a timer. As I currently have no fish in there I do weekly changes, once I get my fish (they are ordered) I will asses as needed, but it is likely that I will move to two per week.

There are plenty of dosing guides out there, google EI doing method and use that as a guide.

Lights are in effect the controlling resource for plant growth - and algal growth! Light effectively determines how fast plants can use the ferts, light is akin to the input energy in a formula! There does come a point where extra light makes no difference - I've experimented with this in the past, using 200W studio MSR lights. But don't get carried away with lighting, too much for your fert regimen (mainly CO2 btw) and you will get algae! And too much can be both on for too long and/or too powerful! In essence you have to tune your CO2 delivery to the amount of light you use, then tune the remaining ferts to that.

All good fun though :) I have a journal going here http://forum.simplydiscus.com/showthread.php?113026-Weeds it may help.