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questions on DIY reactor

jonboy8465

New Member
Joined
29 Jun 2008
Messages
21
I want to build myself an in line external reactor and I would like to ask some questions so i know I`m doing it right.
what length does it need to be? I will be using 1 1/2 pipe.
Will a fluval 105 be big enough to run it on a rena 450?
Is the reactor best fitted on the filter inlet or outlet?
Will the co2 affect the filter internals?
Can i put any filter media into the 105, if so what?
Does the reactor need anything inside to help break up the c02?
Can i do away with the top tee and have the water enter straight in like Ed seeley has? surely this would stir up any collected c02 dissolving it back into the water column?
Am I correct in thinking :
the water enters the reactor at the top?
c02 enters at the bottom?

Many thanks for your time answering these question.
 

Behold

Member
Joined
6 Aug 2008
Messages
219
Location
Basingstoke. Hants
jonboy8465 said:
I want to build myself an in line external reactor and I would like to ask some questions so i know I`m doing it right.
what length does it need to be? I will be using 1 1/2 pipe.

This is up to you. I have gone for 50cm in overall size including any tee's etc as this fits comfortably in my stand.....

ill a fluval 105 be big enough to run it on a rena 450?

Depends on the flow rate. many recomend about 1000 LPH for large reactors.

Is the reactor best fitted on the filter inlet or outlet?

Outlet is best to stop buildup of air in the filter causing noise. but some do pass it throught to aid diffusion

Will the co2 affect the filter internals?

This should not cause an issue. there is possibility of seals breaking down after time but i have not heard of it happening....

Can i put any filter media into the 105, if so what?

If it fits....... Some filters do come empty and you choose what to fit in it.... if a filter comes with media its not meaning it must be used. Although at least 50% should be the right stuff....

Does the reactor need anything inside to help break up the c02?

This is a long term debate... some use bioballs other sponges other spagetti media. I have heard of none being used too.. its all about getting the CO2 in to smaller bubbles to aid surface area on the bubbles (More of them the more surface area = faster diffusion)

Can i do away with the top tee and have the water enter straight in like Ed seeley has? surely this would stir up any collected c02 dissolving it back into the water column?

Again its all debates and noone has a solid answer to what is right. the issue is not un disolved CO2. No CO2 is pure and there are some gases left over which is not water disolvable.. (is that a word???) this is what collects.

Am I correct in thinking :
the water enters the reactor at the top?

Bingo

c02 enters at the bottom?

You got it. as the CO2 enters its big and floats well and will stay in the stream until its quite small. then it is pushed out. by wat time you hope it fully disolved or is pushed around the tank for a bit. once really small it is not very boyant and will move around with the flow rather than rise.

Many thanks for your time answering these question.

No problem. Im sure any wrong answers will be quickly corrected....
 

Ed Seeley

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3 Jul 2007
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3,261
Location
Nottingham
I agree with most of what Behold said.

jonboy8465 said:
what length does it need to be? I will be using 1 1/2 pipe.
It's up to you! I'd look at somewhere between 30cm to 50cm but you could go longer or shorter if it makes it fit somewhere better. Obviously the longer it is then the longer length there is for the CO2 to diffuse so you'll get less bubbles going into the tank as the CO2 will be completely dissolved.

jonboy8465 said:
Will a fluval 105 be big enough to run it on a rena 450?
Is the Rena 450 a 450litre tank? With the fluval 105 you won't have great flow so you may find it hasn't got enough poke to really mix the water and CO2 up. I used my previous CO2 reactor with a 203 and it did a great job on a 180l tank. You could just use an external pump (like an Ehiem universal pump or similar) on a separate loop to your filter. Or you could plumb the reactor into your main filter pipework.

jonboy8465 said:
Is the reactor best fitted on the filter inlet or outlet?
Definitely the outlet as that is the side being pumped back into the tank and you want you CO2 enreiched water straight back with the plants.

jonboy8465 said:
Will the co2 affect the filter internals?
Not in my experience with a CO2 reactor after the filter. In fact many pump CO2 straight into their filter and don't have problems.

jonboy8465 said:
Can i put any filter media into the 105, if so what?
Sure but make sure it doesn't slow the flow any more if you do use this though. If you have another filter then I would either just put a few bits of biological media or don't bother putting any in to keep the flow as high as possible.

jonboy8465 said:
Does the reactor need anything inside to help break up the c02?
No it doesn't, but you can put some open void media to help break the flow up as Behold said.

jonboy8465 said:
Can i do away with the top tee and have the water enter straight in like Ed seeley has? surely this would stir up any collected c02 dissolving it back into the water column?
I prefer this design as I've used it before but either design works well. The tee design has the big advantage of making it easier to access the reactor to clean it. With the straight in design you have to unscrew the reducing bush that screws into the top so it's not quite as easy to access but it can be done without too much hassle. The tee design also mean you don't have to sort the filter pipes to enter the reactor vertically down so it's a bit easier to fit it in.

jonboy8465 said:
Am I correct in thinking :
the water enters the reactor at the top?
c02 enters at the bottom?
Actually I prefer to have both water AND CO2 entering at the top, already in the flow. To do this you need to add the CO2 in line just ahead of the reactor using a reducing tee. The bubbles of CO2 will get jetted down, already mixing with the water, and will swirl and diffuse in the slower velocity water of the reactor. Some gas will build up at the top but the water constantly jetting through it at the top will diffuse all that gas IME.
 

jonboy8465

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Thread starter
Joined
29 Jun 2008
Messages
21
Thank you both for the excellent answers and advise, it`s all been made perfectly clear to me now. yes the rena 450 is 450 ltrs. as i have a selection of different filters i will go with the biggest then, so that i get plenty of flow, the one i will use is the 505. I like Ed`s idea of adding the c02 before the reactor so I will give this a go first and see how i get on. where is the best position for the outlet in the, tank top, middle or bottom? again many thanks for your help.
 

Behold

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6 Aug 2008
Messages
219
Location
Basingstoke. Hants
mine is at the top pointing down a little. i still get light surface movement and it pushes the water down....
 

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