Adding co2

[oldskool]

If my tank is heavily stocked is it neccessary to add an airstone to aid with co2 and will this help the plants and fish. I have about 24" of fish in a 39 gallon tank -

 

[rdd1952]

There are several things to consider. First, if you only have 24" of fish in a 39 gallon, you are actually understocked unless you're talking about current length and not adult length (like you have a 4" pleco which will grow to 18"). Also, depending on the plants you have, you may not need CO2 at all (unless your simply talking about the amount the fish themselves emit). If that's the case, you should have a problem with it as long as you have some surface disturbance from the filter. If you're running cannister filters and aren't getting any surface aggitation, you may want to run an airstone. What is the pH and KH of your water? If you are using a CO2 injection system for the plants, CO2 can drive the pH down especially if you don't have any buffering capacity (KH), you can get a deadly pH crash.

That's maybe kind of confusing but to summarize:

If you are only getting CO2 from the fish, should be no problem as long as there is surface aggitation from filter.
If you're injecting CO2, check your pH and KH to make sure you have enough buffering capacity to keep the pH stable.

One additional note on something that I have wondered about but really don't know. If you are injecting CO2 and then putting an airstone in to keep enough oxygen in the water, are you basically not doing two things that cancels each other. Maybe someone else can shed some light on that.

 

[oldskool]

My fish are not fully grown yet - but i do plan to get another eevn larger tank in the not to distant future so - when they get larger can move them on. The filter i have causes surface agitation and is only on a minimal setting at the moment - it can go a lot higher than it is - so I guess as all is well at the moment there is probally no need to add an airstone.

thanks very much -

Dave

I am running out of brain space for all this information - sometimes i think i worry to much!

 

[rdd1952]

I was the same way when I first started. I tested my water daily to make sure all was well, and in general was always tinkering with the tank. I'm sure the fish were happy when I finally just let things settle down. Since my tanks are cycled and running well, I only test my pH before and after water changes to make sure I haven't reduced or raised it considerably. If I change filters or tinker with any plants or decorations, I'll also check the ammonia and nitrite for a few days afterward just to make sure I haven't started a mini cycle again.

As for your filter, it is ok to not run it wide open as long as you are cycling the water though at least 5 times per hour. Any less than that can lead to problems. If you have a filter that is rated for 300 gph on your 39 gallon, you wouldn't necessarily have to run it wide open but it definitely won't hurt to go ahead and turn it up. You can't ever have too much filtration. The only possible reason to keep it lower is if you have fish that don't like a lot of current. Usually though, community fish like tetras, danios, etc love the current.

 

[Nik_boyd]

The filter i have causes surface agitation and is only on a minimal setting at the moment - it can go a lot higher than it is - so I guess as all is well at the moment there is probally no need to add an airstone.

oldskool, I was for a time using an eheim external filter rated to about 600lt I think in a 60 litre tank turned right down, and now run it fully open on a 180lt. The only problem I found with it turned down was that some nasty yuck collected in the pipes, I don't know if this was down to lower flow rate but I guess so.

Also, if you are considering injecting Co2, I've had a JBL system for about a week and its already made visible differences to my plant growth. quite expensive, but seems good.

Nik