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Discussion Starter · #1 ·
Tried 2 different ISTA co2 reactors now and both were not cutting it. First was an external turbo reactor. Product is good at chopping up the co2 so you dont get bubbles. Down side for me was I use 16/22mm hose and the product is 12/16 mm inlet/outlet. Bought 2 reducers. Return pump hose 16/22 into reducer 16-12mm, into reactor, out of reactor then enlarger from 12-16mm hose and back to DT. After a few weeks I realised my flow rate was less than half what it was without the reactor.

Then bought an ISTA inline reactor which was 16/22mm fittings. Didnt chop the co2 up at all and reduced the flow rate even more than the previous reactor.

I've had it with ebay and these crap reactors so now i've ordered all the parts I need to make a custom reactor. The parts arrive at the end of the week and i will post pics of how it turns out and steps to make it with parts list if it works out well.

Just wondering if anyone else has had experience with reactors and what you thought of them, good and bad points.
 

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Many do use DIY reactors of different styles. I started with the Grigg's style and found no reason to change when the Cerge's came along. Both seem to do much the same without too many problems.
What you found is pretty common on flow though. when you look at putting any fitting inside a tube and then look at the actual opening in that fitting it shows why flow is cut.
You may start with a 12mm opening but when done it may be closer to 8mm? I've never measured it but it is SMALL!
 

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Many do use DIY reactors of different styles. I started with the Grigg's style and found no reason to change when the Cerge's came along. Both seem to do much the same without too many problems.
What you found is pretty common on flow though. when you look at putting any fitting inside a tube and then look at the actual opening in that fitting it shows why flow is cut.
You may start with a 12mm opening but when done it may be closer to 8mm? I've never measured it but it is SMALL!
I started with rex Griggs. After a move i broke it. I had a rigid airline tubing that fed co2 in through the top down about midway through the reactor.

After that i bought stuff to make a cerges. Its lasted through a couple moves and still working. I like it better because it's clear and has a purge button.

If it happens to break i prolly do rex grigg again but build differently. Cerges was like 60 bucks to make. Or maybe a larger cerges idk.
 

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If you have a powerhead in the tank to help circulate the water it is very easy to use that for a CO2 diffuser. In the simplest form you just let the open end of the CO2 hose end under the inlet for the powerhead. The bubbles then get chopped up and blown around by the powerhead. That simple form can be made much more complicated in several ways, which improve the efficiency of the diffuser. I plan to add DIY CO2 to my 65 gallon tank soon, and will start with that simplest form, probably with a piece of bamboo chopstick in the end of the hose to form smaller bubbles.
 

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Built about 5 different griggs never could get one exactly right. High flow, high co2.

Finally slapped a cerges on the end...works like a champ



Not to pick at your design here but it is not what I like to see called a Grigg's style as it has some pretty big changes that do matter.

When I add gas at the side it is out of the main flow of the water and it can create problems. When I push/pull the tubing through an undersized hole and let the gas come out in the center of the water flow, it mixes without creating a large bubble at the top where it can make noise. Just small details that Rex had worked out over his testing and use. When I make changes to a plan, I have to accept any trouble that I create.
Kind of seems wrong to call something a Cadillac if we swap in a VW engine?
 

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Not to pick at your design here but it is not what I like to see called a Grigg's style as it has some pretty big changes that do matter.

When I add gas at the side it is out of the main flow of the water and it can create problems. When I push/pull the tubing through an undersized hole and let the gas come out in the center of the water flow, it mixes without creating a large bubble at the top where it can make noise. Just small details that Rex had worked out over his testing and use. When I make changes to a plan, I have to accept any trouble that I create.
Kind of seems wrong to call something a Cadillac if we swap in a VW engine?
Fair enough. Call it a DIY PVC if that sounds more appropriate.

Fwiw, I know many people use the undersized hole method with good results. but I would never feel confident doing that. Maybe on a low flowing system, but I want to know the connection is secure enough to withstand considerable pressure. Maybe it can? Idk, never tried it.

I did use a different style T on a couple of them, couldnt tell that it made any difference.

(This design would work great with 200-300 gph of flow, and maybe 7-8 bps)




What made a difference was playing with the length, a cut off valve to increase pressure, and various amounts of bio balls inside.

Not doubting what you say, just that the undersized hole thing isnt something I would do.

If I had it to do over again I would maybe try a bypass design. But at this point, and because I still had ample flow to spare, it was easier to just stick a ... "water filter housing type" on the end. :)
 

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Discussion Starter · #9 ·
Thanks for all the comments. My plan is to make something like this.

I am not 100% sure on the name it's called by people but it looks like a good one to start with. I have changed the design by replacing the white 2" PVC pipe with clear pipe so I can see inside it. Now that I look at other ones posted, I think I may need to change my idea again. The plan was to do this:

40mm OD x 36mm ID clear pipe x 600mm long


40mm PVC Reducing Bush Glue x 3/4" FBSP Fitting (one for each end of the clear pipe


3/4" male threaded x 16mm hose tail barb (one for each reducing bush)


1/8" male threaded x 1/4" (6mm OD) hose fitting (CO2 pipe)


Then throw some bio-balls into the reactor to help break up the CO2. Any and all comments are welcome as I haven't built it yet so if anything can be changed to make improvements, I'd appreciate the comments before I start.
 

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You are going to be SO VERY glad to have clear pipe!

If you can spare the flow, adding a cutoff valve after the reactor can help tremendously. Closing it just a little will increase the internal pressure. Pressure dissolves CO2 faster than anything.

Bio balls help a lot too, but they will cost you some flow. Not very much ime, but some

Here is another design that worked great. It's basically a longer version of the one above.



If you have a powerhead in the tank to help circulate the water it is very easy to use that for a CO2 diffuser. In the simplest form you just let the open end of the CO2 hose end under the inlet for the powerhead. The bubbles then get chopped up and blown around by the powerhead. That simple form can be made much more complicated in several ways, which improve the efficiency of the diffuser. I plan to add DIY CO2 to my 65 gallon tank soon, and will start with that simplest form, probably with a piece of bamboo chopstick in the end of the hose to form smaller bubbles.
Ive done this on a couple different tanks and it works great if you dont mind a mist. Pre-diffusing with a chopstick makes all the difference in the world. A piece of regular cotton ball packed tightly into the line works too.



 

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Discussion Starter · #11 ·
The only thing I didnt think about was being able to take it apart IF I ever need to. Ive seen some reactors where they have 2" - 2" male/female couplers so you can unscrew it. Once I put the bio-balls in and glue it all together, I won't be able to take it apart. Do you think I will need to ever take it apart? Will the bio-balls need cleaned or replaced after a period of time? If so, I will have to use different connections.
 

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All those couplings you see in mine...are from taking it apart to change something. In my case, taking it apart means cutting it, then splicing it back together with a coupling. A simple procedure, but it kinda looks rough after 2 or 3 times.

The bio balls may need cleaning once every year or two (guessing) or maybe never, idk. Maybe someone who's used them for a long time can chime it.

My guess is if you need to take it apart any time soon, it will be to modify the design. You have the advantage of being able to see what's going on inside. So trial and error should be minimal.

The ability to unscrew it would certainly be convenient though.
 

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Discussion Starter · #13 ·
Do you think i should make the reactor as long as possible? Not sure if longer has any downsides? My pipe is 600mm long. Would this be long enough or should it be shorter?

Also, should the intake be at the top and outlet at the bottom or does it not matter? And the co2 line, should this be at the top or bottom?
 

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Water from the filter goes in the top of the reactor, exits the bottom then on to the tank.

Most designs have the co2 going in either in the center, or somewhere in the top half area. The idea being CO2 bubbles try to float up against the water flowing down, swirl around to the point they fully dissolve before exiting the bottom. If you put the CO2 line too low bubbles will just blow out the bottom.

Longer is better for higher flow rates because the co2 says inside longer, aka more dwell time. Too short and you'll get a mist of undissolved bubbles coming out. Also, the degree of pressure inside the reactor, and anything like bio balls will also have and effect on how fast/efficient the co2 dissolves. So if you have a lot of pressure, you can get by with a shorter reactor because the CO2 will dissolve faster.

How long to make it? Depends on your specific flow rate, how much pressure is inside the reactor, how much co2 is being added, etc. Somebody may know a good universal size, I had to do several before getting one right for my individual set up. But I cant think of a downside to making it as long as possible.
 

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Discussion Starter · #15 ·
This is my current sump setup, without the inline reactor as I haven't made it yet but this is my plan. Hopefully it works out OK and does what I need. I am starting to think that adding a cut-off valve might be an idea so I can increase the pressure a little as you suggested.

I was going to put my old internal filter into my tank as it has a fitting for an air line but I dont want it to be in the display tank as it looks ugly.
 

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This is what I did....I've done the cerges and the Griggs...all work fine...except I was tired of compromising the filter. At one point I had to have two filters to compensate. So I bought the small ISTA rigged one of those Rio pumps and put the whole thing in the tank.



If you don't believe it works...well look at my tank


Pros....
Cheap as hell...especially if you have one of those pumps laying around like I did.
It's in the tank. No worries about noise or leaks. Ugly? Yes but can you see it in my pic? No.
Don't want to say 100% dissolved rate but pretty damn close I would say. Rarely see any bubbles.

Cons...
None. Unless you can't hide it behind anything in your tank.
 

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This is what I did....I've done the cerges and the Griggs...all work fine...except I was tired of compromising the filter. At one point I had to have two filters to compensate. So I bought the small ISTA rigged one of those Rio pumps and put the whole thing in the tank.



If you don't believe it works...well look at my tank


Pros....
Cheap as hell...especially if you have one of those pumps laying around like I did.
It's in the tank. No worries about noise or leaks. Ugly? Yes but can you see it in my pic? No.
Don't want to say 100% dissolved rate but pretty damn close I would say. Rarely see any bubbles.

Cons...
None. Unless you can't hide it behind anything in your tank.
Yeah. Only drawback here is i'm working on getting all the equipment out of the tank I can lol.
 

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Discussion Starter · #18 ·
Now I have a very technical question. My pipe is 40mm OD x 36mm ID x 600mm long. My bio-balls are 32mm in diameter. The volume of water my pipe can hold is 610ml or 0.61 litres. Once I add in the bio-balls, this will be reduced down to around 130ml or 0.13 litres. I know that by having a high water flow into the reactor + very little volume inside the reactor = high pressure. How much volume should I have once the bio-balls are in? Not sure if I need more space inside the reactor for water or if this will be OK....
 

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So basically 3/4" ID pipe? (sorry I cant think in metric)

No idea how or if that will work. Not very well if I had to guess. Most reactors use a 2" pipe, or maybe 1 1/2" for smaller ones (ID).

Not sure because Ive never tried it, but with a pipe that small bubbles are probably going to shoot right through. There needs to be a certain amount of dwell time to give the co2 a chance to dissolve. With a pipe that small you will have high velocity, not necessarily high pressure.
 
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