[fishnovice]

Hello all,

I am obviously new to the board, and new to aquariums in general. We have a "baby biorb" tank in my sons room. He has a simple betta, and we recently decided to add a pleco to help with housekeeping.

In the interest of being more natural, and pretty, we've added some bulbs which have finally decided to grow... very slowly, then turn brown and die.

After a little internet research, I decided what the 4 gallon tank needed was a shot of CO2.

I used a 3L bottle, with a 500ml bottle for a bubble counter, and a common recipe for DIY CO2. Worked like a champ. The CO2 was fed into the tank via the existing airstone. Yield was approx 1 bubble per second.

Here's my problem. We left for a while, and upon our return, found the pleco had managed to get lodged into the tube, where the CO2 was being introduced. (For those of you not familiar with the "baby biorb", it has a cylindrical tube in the center of the "orb" shaped tank, which contains the airstone at the bottom. The bubbling causes a water current, which draws water through a bio filter substrate.) I dont know how long he was trapped there, breathing a LOT of SMALL CO2 bubbles, but when I got him out and back into the tank, he was obviously distressed. Occasionally he would go to the surface and gulp air.

The next morning, the pleco was dead. I am crushed, and so is my son. I am responsible for his demise- if I'd never performed this DIY CO2, the fish would be fine.

I am looking for advice as to-

1. Do you think the tank was overloaded with CO2? Thus, stressing the pleco to death?
2. Do you think the concentration of the CO2 he breathed, when trapped in the tube caused his death?
3. Or, perhaps a combination of the stress of the tube, and the CO2.

I thought I was doing something smart by using a larger sized container, and a higher volume of water. (longer lasting co2)

I am terrified to attempt it again at this point... and the betta is lonely. I would hate to kill another fish due to my lack of experience and knowledge...

Thank you very much in advance for your advice,

 

[fishnovice]

Thanks for the reply.

The pleco had been in the tank for about 3 weeks. There was a bit of algae for him to graze upon, and he did usually at night. We also purchased some algae wafers to supplement his diet- he ate those as well.

There was no room air being fed into the airstone, only the CO2. It is a small tank, that is why I was concerned in hindsight about perhaps overdosing with CO2. The bubbles were very fine, as the pressure was low, but a steady bubble count of at least 1 per second remained constant for probably 12 hours.

The only thing further I could add that might shed some light, is I did implement a "bell" into the system to catch the CO2 bubbles, (also found this information on internet regarding DIY CO2). So, as the bubbles rose, they were captured in an inverted cup-like container, roughly three times the diameter of the tube- I dont know how much additional surface area of the water was being constantly exposed to the CO2 by using this method- but it looks like it is a common modification to help increase absorption of the CO2 by the water.