need advice: CO2 reactor for 125 gal

[cvar]

I'm switching to hi-tech!

What sort of CO2 reactor should I build for a 125 gal?
Would you suggest a large CO2 reactor, or 2 smaller ones?

I prefer DIY (will need clear PVC), but I'm OK buying something like a CarbonDoser EXT5000 from aquarium plants dot com. But I'm unsure whether it's enough.

I want to avoid micro-bubbles and more hardware inside the tank.
I get micro-bubbles already, as a nuisance from occasional cavitation of impeller.

For DIY, is it better to use 3" PVC or 2" PVC?
How long? My cabinet is only 21 inches tall, inside. Kinda tight.
And would embedding an airstone inside reactor be better for dissolution?
How about embedding an old small power head?
Those would require an opening for maintenance or removal. But how?

I have 2 canister filters: Eheim 2262 and Eheim 2028. The big one moves about 600 gph and is plumbed with 1 inch PVC. The smaller one moves 150gph and has its original 5/8 hose. Together, I have lots of flow. I could tie into IN or OUT of either filter, or both.

Plants are growing well, on Excel, which is just too $$. Hence the CO2.
I have 2x T5HO lights (daylights) for 12 hrs/day, and lots of community fish: CL, SAE, tetras, swords, corys, etc.

I have read many posts about CO2 reactors, DIY & not. But they're usually designed for mid-sized, low flow situations (eg, 1/2 inch piping). Little mention of bigger tanks.

Any ideas? Please help?

 

[Gerryd]

Hi cvar,

I have read many posts about CO2 reactors, DIY & not. But they're usually designed for mid-sized, low flow situations (eg, 1/2 inch piping). Little mention of bigger tanks.

I think you need to search more... Tom and many members have 180 and larger. Many 90+ out here in Barrland as well

May I suggest lowering the photo period to 8-9 hrs max? no need for 12....

The size/diameter of the reactor and the inlet/outlet size is mostly predicated on the amount of flow you want to the reactor...larger reactors also allow for ceramic rings, bio-balls, etc to help keep the c02 in the chamber a bit longer...

I would NOT use a PH inside the reactor.

I would also NOT run the reactor with either filter. Let them do what they do best. Use another pump to run the c02 if possible.

Running two smaller reactors, one outlet at each end of the tank, is a nice solution as well for larger tanks.

Don't forget to think about surface agitation to introduce more 02 during the photoperiod when c02 is introduced...

 

[cvar]

Ok, the Co2 reactor hunt continues....

I was originally hoping to tie it into the big canister output plumbing (inline, or venturi, or mazzei), but you wouldn't do? Another pump means yet another set of pipes to/from the tank. Sigh. I was hoping to avoid that. My tank is not against a wall, so it's viewable from both front & back.

If bioballs improve a reactor, that way, would an fine airstone help too? Would increasing reactor diameter from 2" to 3" dia. do anything at all?

BTW, I might already have good surface agitation? There's a vigorous 6" diameter air-stone blowing lotsa pretty air bubbles, plus the 1" dia. spray bar emits the big canister 600gph output, plus I have a large HOB filter (Whisper 60) that stirs the surface a bit more. All those are on 24/7, and are spread evenly around the tank. But there's also a full glass top about 1" above the water line. Is that bad for the fish?

It seems I'm about to embark on an adventure of experimentation!