Using FBF for CO2 reactor?

[FeatherfinFan]

I've got a Lifegard600 FBF that I'm thinking of converting to a CO2 reactor for a new 100 gal tank and wanted to know if it's a good idea.

It's quite long at just under 2 feet and has a good water capacity, and since it's clear I thought it might be a good candidate for the project.

Since the water flows downward into the chamber then up through the media this may not make it as efficient as the downward-flow units but I was thinking of loading the chamber w/ BB-sized gravel to help break up the bubbles.

Anyone else tried this or have any comments or suggestions?

Also, I've got a Rio1700 to power this reactor and just wondering what flow rate works best for reactors? This pump puts out around 600GPH in this configuration but can easily be cut down if needed. I'd be connecting the CO2 to the venturi line on the powerhead fitting.

[Oqsy]

should work pretty well...

i'd suggest not running the co2 into the venturi, but directly into the lowest point in the chamber so the bubbles will fight to float up against the current, and shrink along the way... this provides the most efficient diffusion rates.

as a bonus with having the venturi, you can attach it to the top of the chamber where gas collects in pockets, allowing them to be sucked back into the power head, chopped up, and more easily pushed out of the reactor (this is mostly O2 and not CO2, and should be eliminated from the reactor to increase it's efficiency) many people eliminate the gas pocket with a "release valve" which is just an airline or valve connected in the same position that can be opened to allow the o2 to escape into the air. (kind of a reverse venturi... doesn't necessarily work on the venturi principle, but it uses an airline to remove air from the chamber instead of put it in)

with a flow rate at 600gph, you'll blow all of your gas straight out of the reactor and into the tank without diffusing it, unless this unit is much larger than i'm picturing in my head... a flow rate of 200-300 gph is probably still on the high side for most applications, but people with canisters at this flow rate are able to diffuse CO2 very effectively.

Oqsy

[Oqsy]

i just looked at a diagram of the fluidized bed filter you've got... very nice. in fact, forget what i mentioned about tampering with it to allow for CO2 delivery from the bottom of the chamber... you should't mess up such a nice filter for something that it will probably do just as effectively without changing. go ahead and try injecting into the venturi, see how far the bubbles get, whether anything starts to build up in the filter (gas), and if you see any bubbles leaving the system back into the tank, as this will be the best gauge of how well it's churing the CO2 (aside from the obvious ph/kh tests)

one though i've had... is there a way to adapt one of the bottom inflow barbs down to 1/8" and input your CO2 there without having to alter the filter itself? let me rephrase that, as i imagine there's a way, it just depends on whether or not it's a practical endeavor.

a fair amount of pool filter sand or fine gravel should do the trick just fine... i'm picturing bubbles going into the gravel, and none coming out. in fact, with that water flow rate, you might also reap the benefits of the FBF as it was intended in addition to having a nifty CO2 reactor. good thinking... let us know how it goes, and give us some pics if you can

Oqsy

[FeatherfinFan]

Thanks Oqsy for the detailed reply
I'll take your advice and try it without any mods first and use sand rather than gravel. I think I'll also just get a small powerhead rather than strangling the output of the large 1700. I guess a 200GPH rate is what I should try. I should be able to adapt one of the lower lines to a small hose fitting. I guess I'll try it through the venturi first and see if its' working OK.
Thanks again, and I'll keep you posted

[Oqsy]

excellent... when you say "sand", do you mean pool filter sand (larger grains, similar to fine gravel) or finer playsand, etc?... everyone's definition of "sand" and "gravel" is a little different, and can lead to confusion. what kind of media was in the filter before? were you using it on a marine or fw tank? after I entered my second post, i thought about it a bit more, and realized that ehfisubstrat pro might be an even better choice, as it would require less maintenance (no worries about compaction with reduced flow rate through the filter) provide LOTS of surface area, and make the bubbles dance around like a cat on a hot tin roof. of coures, this isn't the cheapest media in the world ($18 for a liter? YIKES!), but if you already have some or know of a way to get it or something similar cheap enough, it could be worth a shot... it's probably just best to wait and see what happens with your current plan. once again, keep us up to date and post pics of progress

Oqsy

[FeatherfinFan]

I've actually got (2) of the FBF600s running on my FW 300gal 2tank+sump system and it's overkill for my system so I'll just remove one of the FBFs. Thye use fine silica/blasting sand right now, but I bought 200 pounds of EcoComplete Plant Substrate and since CaribSea was so kind to replace the bags I've now got extra gravel form that so I may just use some EC.

[AZFIsh1]

Doesnt the water enter at the bottom and travel up in those? Wouldnt you have to reverse the flow to get the bubbles fighting while they travel upward against the current. If thats the case you may want to run it with no sand or gravel in it at all. I may be wrong here.... not sure.....

[FeatherfinFan]

Doesnt the water enter at the bottom and travel up in those? Wouldnt you have to reverse the flow to get the bubbles fighting while they travel upward against the current. If thats the case you may want to run it with no sand or gravel in it at all. I may be wrong here.... not sure.....

The current enters through a tube in the top and the tube exits in the bottom of the chamber, allowing the current to flow upward through the media. I was thinking the constant contact w/ the media would be enough to break up and dissolve the bubbles. I guess I'll just get my tank up & running and give it a shot, I'll let you know if it indeed works as I hope it will

[AZFIsh1]

Yeah post that for sure. I have a couple old FBF filters, cant remember the manufacturer. Acrylic cylinders. I would be interested in trying this as well. Could be bio and reactor all in one.