My DIY Reactor doesn't work - The Planted Tank Forum
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post #1 of 19 (permalink) Old 10-01-2017, 12:09 AM Thread Starter
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My DIY Reactor doesn't work

The first thing I noticed after hooking this up was my flow went way down. The CO2 for the most part collects at the top. My pH drop is 0.2 to 0.4 max, regardless of how much I inject.

I'm using a Fluval 206 with 5/8 ID tubing.

Because the reactor is tall, the tubing goes up about 10 inches, then down about 2 feet, then back up 4 feet to the top of the tank.

Any ideas to make this work better?
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post #2 of 19 (permalink) Old 10-01-2017, 01:15 AM
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Your filter is probably not strong enough for that big of a reactor.

Iíve never used nor built a Griggs reactor, but all the ones Iíve seen have the Co2 injected midway down the reactor and not the top like yours. Not sure if thatís an issue but at least an observation.
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post #3 of 19 (permalink) Old 10-01-2017, 02:18 AM
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Flow might be too low.

Also your Co2 input should not be at the top. The actual design calls for it to be placed somewhere along the main body of the reactor so the bubbles raise up and get caught in the stream of water. By adding the Co2 where you are adding it, it probably is just creating an 'air' pocket.
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Last edited by slipfinger; 10-01-2017 at 03:05 PM. Reason: edit
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post #4 of 19 (permalink) Old 10-01-2017, 02:56 AM
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I have two plummed on my system. The CO2 injection is on the top. If you are not getting these to produce dissolved CO2, crank up the low pressure gauge on the regulator, and or increase bubble count.
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post #5 of 19 (permalink) Old 10-01-2017, 02:47 PM Thread Starter
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Thinking about it some more, I think it would work as-is if my flow rate was higher. While there are elevation changes in my setup, the total pump head is not changing. That leaves piping losses as the cause of the flow reduction.

The 5/8 tubing appears bigger than the standard ribbed tubing. Perhaps I can eliminate the elbows/choke points to get my flow back.

I really don't want to buy a $150-200 filter to get this to work.
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post #6 of 19 (permalink) Old 10-01-2017, 04:01 PM
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I also added some plastic bioballs to mine - they help break up the co2 as well - did seem to make a small difference.
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post #7 of 19 (permalink) Old 10-01-2017, 04:04 PM
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I would move the C02 inlet more toward the center of the reactor. As previously mentioned you are probably creating a pocket up there. What's the gph of the filter and what is the diameter of the tubing?
In my experience flow will always severely impacted by a reactor. It is a necessary component of dwell time. As long as you are getting adequate dissolution your best bet is a power
Powerhead. I have an AC50 under the output of the 2215 I use for one of my reactors. Change up the design of the reactor and add a filter or powerhead.

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post #8 of 19 (permalink) Old 10-01-2017, 04:19 PM
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Two major points are at play. One is that flow will always be restricted when we add fittings that go inside the tubing. Look at the hole in the center of the fittings compared to the hole in the tubing. I find water flow works somewhat the same as traffic flow in that the same things get the same results. If we take a highway and force the traffic into sharp corners, it slows. If we force it into smaller/fewer lanes, it slows. Wider, smoother corners can help but doing away with corners works even better. Fittings are the main killer, though, and they are hard to eliminate!
The second point I see is that this is no longer a "Grigg's" reactor as one of the basic items has changed. The CO2 is injected at the top and side instead of into the main center of the water flow. This lets it simply ride on top of the flow where little is in the water but only on top of it.
I find lots of reactors that are somewhat similar to the Grigg's but don't work like the Grigg's. When we change a design, we have to also assume the failures if we introduce them.
This is the design as close to original that I use.
How To Build A CO2 Reactor | Build a Regulator | Test Kit
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post #9 of 19 (permalink) Old 10-01-2017, 05:10 PM
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Quote:
Originally Posted by Nlewis View Post
Your filter is probably not strong enough for that big of a reactor.
I agree, IME you will need 2x-3x larger canister filter to run a reactor and you won't require additional pumps in aquarium. Also keeping the canister clean(weekly) will help keep CO2 stable in the tank.

Quote:
Originally Posted by slipfinger View Post
Flow might be too low.

Also your Co2 input should not be at the top. The actual design calls for it to be placed somewhere along the main body of the reactor so the bubbles raise up and get caught in the stream of water. By adding the Co2 where you are adding it, it probably is just creating an 'air' pocket.
Also agree, I injected CO2 1"-2" off the bottom of the reactor

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Originally Posted by ice9 View Post
I also added some plastic bio-balls to mine - they help break up the co2 as well - did seem to make a small difference.
This will also reduce the flow. I've used a DIY reactor for 5+ years without bio-balls. IME, no issue with CO2 dissolving and easier to clean.

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Originally Posted by PlantedRich View Post
The second point I see is that this is no longer a "Grigg's" reactor as one of the basic items has changed. The CO2 is injected at the top and side instead of into the main center of the water flow. This lets it simply ride on top of the flow where little is in the water but only on top of it.
I find lots of reactors that are somewhat similar to the Grigg's but don't work like the Grigg's. When we change a design, we have to also assume the failures if we introduce them.
agree

Chris
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post #10 of 19 (permalink) Old 10-01-2017, 06:43 PM
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The reactor is too large for the filter. You could use one half that size with a 206 and PlantedRich's comments regarding flow through the reactor and the point of CO2 injection are all correct.
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post #11 of 19 (permalink) Old 10-01-2017, 11:54 PM Thread Starter
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I took a hacksaw to it and will rebuild it. To increase flow, I'm going reduce the number of elbows and increase the hose connection sizes, at least on the outlet to the tank because the Fluval ribbed hose can fit around a 3/4 inch barb.

One thing I noticed while taking the reactor apart is there was a very large area for CO2 to accumulate inside the 1" to 2" PVC adapter. See photo. I'll use silicon to fill in areas like that on the rebuild.

I'm a little concerned about drilling a hole in the chamber and pulling the CO2 tubing though. Doesn't it need to be sealed?
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post #12 of 19 (permalink) Old 10-02-2017, 03:28 AM
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wow

installed 2 rex grigg 24" reactors with bypass on my 200 G setup with reef style overflow and open sump on thursday. I now have too much dissolved CO2. A good problem to have! btw, I researched and tried pretty much every reactor on the market for my system, which is big and has extreme high flow - reef style overflow - and this setup is the only one that produced an appropriate level of dissolved CO2.

Here is my sump...a modified Lifereef wet dry filter. Removed the two bioball chambers and plumbed the drains into the side. Am running carbon, bio pellets, and phosphate remover in the three media reactors.
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post #13 of 19 (permalink) Old 10-02-2017, 03:37 AM
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Quote:
Originally Posted by paulbert View Post
I took a hacksaw to it and will rebuild it. To increase flow, I'm going reduce the number of elbows and increase the hose connection sizes, at least on the outlet to the tank because the Fluval ribbed hose can fit around a 3/4 inch barb.

One thing I noticed while taking the reactor apart is there was a very large area for CO2 to accumulate inside the 1" to 2" PVC adapter. See photo. I'll use silicon to fill in areas like that on the rebuild.

I'm a little concerned about drilling a hole in the chamber and pulling the CO2 tubing though. Doesn't it need to be sealed?
Yes, it needs to be sealed. You can install a tee in the center with a threaded reduced and use the threaded barb fitting you currently have.

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post #14 of 19 (permalink) Old 10-02-2017, 01:52 PM
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Quote:
Originally Posted by paulbert View Post
I took a hacksaw to it and will rebuild it. To increase flow, I'm going reduce the number of elbows and increase the hose connection sizes, at least on the outlet to the tank because the Fluval ribbed hose can fit around a 3/4 inch barb.

One thing I noticed while taking the reactor apart is there was a very large area for CO2 to accumulate inside the 1" to 2" PVC adapter. See photo. I'll use silicon to fill in areas like that on the rebuild.

I'm a little concerned about drilling a hole in the chamber and pulling the CO2 tubing though. Doesn't it need to be sealed?
No, it does not need to be sealed if done correctly. What many miss is that the Grigg's design has numerous small design features based on the KISS idea. And those ideas have been time tested and found to work. Most failures are not caused by the design but the lack of trust and the way the work is done. When CO2 is injected near the center of the reactor, the tubing can't be placed correctly with the tools most of us have.
The hole has to be small to compress the tubing correctly. To get that oversized tubing through an undersized hole requires using the method Grigg's had worked out. If you can simply push the tubing through the hole, you've missed the point, not followed directions and it will leak! If you have used a fitting to inject the CO2, you have not followed directions and there is a reasonable chance you will get noise as the CO2 doesn't enter the water where the flow is highest.
So my point is that there is one way to build a Grigg's reactor and it works but there are numerous ways to build a reactor of YOUR design and some work while some fail. Your choice but then it is also your head that the blame has to fall on, rather than the Grigg's design.
Again the KISS principal comes into play. Build it as designed and it works so well that it is almost a "standard" in the hobby or build it your way and it may not work as well.
To make it work, you should have to work to get the tubing pulled in to the center of the water flow! If it is easy, you did it wrong!
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post #15 of 19 (permalink) Old 10-02-2017, 10:18 PM
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quote:
To make it work, you should have to work to get the tubing pulled in to the center of the water flow! If it is easy, you did it wrong!

This may seem to be an overly critical statement so I thought maybe some further explanation might make it seem more logical.
This is a type seal which many doubt but when we look closer, there should not be so much concern as it is a really common type sealing method. We often deal with compression seals. It sometimes used under different names but they all use compression to make the seal. Some common places where compression is used are so normal we never hesitate to use them.
The seal at the CO2 tank, the one at the end of a hose when we screw it on the faucet, even the place where we turn a washer type faucet off, are all using compression to seal.
All it takes is getting enough compression to stop leaks. But when we use the tubing itself to make this seal, it seems wrong. When we screw the reg onto the tank, we have to get enough pressure to compress the washer and stop any leak, so it should be no big thing to imagine that we need to do the same with the tubing.
We have to pull the tubing through a hole small enough to compress it and make it seal against the hole sides. To do that we have to use a small hole and the right technique to get the tubing pulled through.
The way Mr. Grigg's says to do it works but it does take some effort. We have to be able to drill a small hole, cut the tube end to a very sharp point and then reach inside with pliers to wiggle and force the tube through far enough to let the CO2 come out in the center of the water flow. You can't normally reach in far enough to use a hole in the center of the pipe.
Compression sealing is very simple and certainly works but we also have to do it right.
The beauty of the Grigg's reactor is in the simple design as it really does work.
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