DIY CO2 in large tank

I think a 55gal. tank is pretty much the limit for *effective* use of DIY CO2. And, IME it really becomes a chore for that size tank.

When I was doing the DIY in my 55s, I was using 4 bottles in each, daisy chained together to get the kind of absorption I felt was necessary, and that was with 2watts/gal. in one of the 55s and 3watts in the other. Also, I was changing off one bottle a week, on a rotation basis, to keep the mixtures fresh, for an approximate of 18 - 20ppm. This, in short order, became drudgery.
My advice is that if you have the money, pressurized is the way to go for your sized tank.
You can get a system up and running for a bit over $100 if you can find a used 10 or 20lb. tank for sale, in your area. Don't buy a new one. Too expensive, and many welding shops trade off tanks rather than filling on the spot, so you'd end up with a used one anyway. They are not difficult to find.
Then it will cost you anywhere from $9 - $18 every 6 - 9 months to get it refilled or exchanged for a full one.

Len

I know I read someone doing DIY in a 90g. Maybe it was in DIY Forum? :idea2:

I did it in a 75 gal. I had three bottles into one line. It worked quite well. I set it up so I would change one bottle at a time every week.

Then I broke down and got a co2 system and never looked back.

LtM

I was thinking that 2 Jello Co2 bottles should work. You might need to go with 3 of them but they last about 3 months on my tanks. But that would cut it down to changing one every 20 to 30 days depending on your room temp.

This is a re-post from DIYMatt (I hope he doesn't mind )

Sure, here it is for my 75 gallon. I use two bottles in rotation. These are easily lasting a month for me, so now I change one bottle every 10-14 days. I think the larger bottle with more water is key to my success. You can adjust this recipe to fit your needs. Just adjust the jello to sugar ratio. More jello = slower,longer production. More suger = faster, shorter production.

For my 75g:

1 packet Jello
3 cups sugar
about 2/3-3/4 gallon water
1/2 packet champagne yeast form homebrew store
1/2-1 tsp baking soda(your KH is half mine)
1 tsp sugar
1 gallon juice jug with good seal(use teflon tape if seal is bad)

I put the water into a large pot and heat until it boils then I stir the jello and sugar until it fully dissolves. I let it cool some then pour via funnel into my jug. Then, I loosely seal it and let it sit overnight to fully set up. Then, the next day I rehydrate the yeast per the yeast package directions plus I add the 1 tsp sugar and I would add the baking soda here. I dechlor my tap water first to make sure I am not harming the yeast when I rehydrate it. The pkg directions on my yeast say float the yeast in about 4 oz of 105 degree water for 15 minutes then stir and pitch the yeast. I mix the sugar and baking soda with the water before floating the yeast. Adding the sugar ensures the yeast stay alive for the 15 minutes and gives the whole thing a jumpstart. I do mine in the evening, so I hook it up right away. It usually only takes an hour or two to get going using this method. If you use a higher ratio of jello it will take longer. I think properly rehydrating the yeast is one of the keys to getting consistant results from DIY CO2. The other is good seals on all your fittings, especially with two bottles daisy chained together. I silicone all fittings, including my check valve.