[Thenoob]

Hey Everyone,

I've been reading a lot recently about the differnt kinds of reactors and its a bit overwhelming so I have a couple of questions particular relating to their use with sumps.

Question 1: Cerges vs Rex Griggs.
To me it seems like a cerges would work better with a sump from a headloss perspective since you don't have to pump the water in through the top of tall reactor, have it flow downward, and then go back up again to the tank. However I've seen a lot of concerns about gas buildup in cerges reactors and was wondering how big of an issue it actually is.

Question 2: Plumbing
I'm planning to run the reactor off the main return pump. I should have plenty of flow to so this as I have an adjustable 660 gph pump and this is for a 20 gallon tank and 10 gallon sump. My question is the best way to plumb this. I am planning to the reactor off the main return. For the reactor outlet, I could have it discharge back into the sump near the pump inlet essentially making a ancillary closed loop. The other option I'm thinking about is having the reactor output T directly back into the return creating more of a bypass loop.

From what I've seen most people seem to do the first option. It is definitely the easier of the two but I wonder if it leads to more co2 loss due dumping co2 enriched water back into the sump. Does anyone have any experience or thoughts on either method

Question 3: Cerges housing
If I go with the cerges, which I'm leaning towards, I'm having a hard time on filter housing selection. Since this is a small tank I assume a standard 10 inch housing would be more then enough, even with extra co2 loss from the sump? Second, is the pressure relief valve I'm seeing on some of the housing useful? I can forsee it being used for degasing gas build up if it's an issue. Lastly, I've been reading reviews for some of the cheaper option on Amazon have seen some issues with leaking from the in and out ports. Anyone have any experience with this?

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[EmotionalFescue]

Question 1: Cerges vs Rex Griggs.
To me it seems like a cerges would work better with a sump from a headloss perspective since you don't have to pump the water in through the top of tall reactor, have it flow downward, and then go back up again to the tank. However I've seen a lot of concerns about gas buildup in cerges reactors and was wondering how big of an issue it actually is.

I have never used a rex reactor, but I have built and used three separate cerges style reactors in sumps. Gas buildup is only an issue if the reactor isn't tuned properly (i.e., if the flow through it is too low relative to how much gas you're pumping in).

Question 2: Plumbing
I'm planning to run the reactor off the main return pump. I should have plenty of flow to so this as I have an adjustable 660 gph pump and this is for a 20 gallon tank and 10 gallon sump. My question is the best way to plumb this. I am planning to the reactor off the main return. For the reactor outlet, I could have it discharge back into the sump near the pump inlet essentially making a ancillary closed loop. The other option I'm thinking about is having the reactor output T directly back into the return creating more of a bypass loop.

From what I've seen most people seem to do the first option. It is definitely the easier of the two but I wonder if it leads to more co2 loss due dumping co2 enriched water back into the sump. Does anyone have any experience or thoughts on either method

I have tried both and greatly prefer the bypass option with the reactor hooking back to the return line instead of dumping into the sump. It's much more efficient. Just T off the return to the reactor, and then T back on with a ball valve in between.

Question 3: Cerges housing
If I go with the cerges, which I'm leaning towards, I'm having a hard time on filter housing selection. Since this is a small tank I assume a standard 10 inch housing would be more then enough, even with extra co2 loss from the sump? Second, is the pressure relief valve I'm seeing on some of the housing useful? I can forsee it being used for degasing gas build up if it's an issue. Lastly, I've been reading reviews for some of the cheaper option on Amazon have seen some issues with leaking from the in and out ports. Anyone have any experience with this?

The pressure release is very useful if you have a back-pressure valve. I usually always install them on my reactors and I'm always glad I did. If you have a gas pocket, close the back pressure valve and depress the pressure release button. All of your gas will be instantly purged. This is particularly useful on a reactor in a sump because the return can siphon and pull air into the reactor when you shut the power off. I have bought several housings from ifilters.com and they've all been great. A 10"x2.5" housing would be fine for a 20g, but I prefer the 10x4.5 like this one.

 

[Thenoob]

Thank you @EmotionalFescue, this is super helpful!

I am think I will probably go with a cerges reactor. I did want to find out more about the valve layout you mentioned. For the pressure valve, is that located between the reactor outlet and main return line? If so is that the only valve used or is there a second valve on the main return line? I ask because I'm trying to think back to my fluids class and it seems like a single valve on the reactor outlet wouldn't make much a difference in the water pressure in the reactor since the main return line would still be unrestricted. If I'm remembering things correctly (fluids was not my strong suit), a second valve placed on the main return between the reactor inlet and outlet would allow much strong control of reactor pressure. Restricting the main return line would cause the pressure below the valve to be higher then above. Since the reactor inlet is unrestricted the reactor pressure would be essentially equal to that of main return below the valve. The second valve on the reactor outlet is also then needed to restrict the reactor outlet to maintain the pressure differential and ensure the flow isn't entirely rerouted through the reactor.

No idea if the way I described it made any sense. I can draw it out if it didn't. To make a long story short, one valve or two?

 

[EmotionalFescue]

Two valves

 

[Thenoob]

The pressure release is very useful if you have a back-pressure valve. I usually always install them on my reactors and I'm always glad I did. If you have a gas pocket, close the back pressure valve and depress the pressure release button. All of your gas will be instantly purged. This is particularly useful on a reactor in a sump because the return can siphon and pull air into the reactor when you shut the power off. I have bought several housings from ifilters.com and they've all been great. A 10"x2.5" housing would be fine for a 20g, but I prefer the 10x4.5 like this one.

How difficult is it to tune the reactor with an opaque housing? I checked out filters and for some reason, the shipping seems to be very high, $25 for the lowest price shipping option. Due to this, I've been looking to amazon, and all of the clear housing I am finding seem to have lots of issues with leaking. The opaque housing appear to be stronger and more affordable I'm worried turning might be a challenge.

 

[Phil Edwards]

If space is an issue with a Cerges (they need to be big), you can do the same as EmotionalFescue diagrammed with a Grigg's style reactor. I did a bunch of those before back in the day before Cerges were a thing. Adding bioballs or larger lava rock in the reactor chamber helps too as it creates turbulence to improve dissolution.

If you have the space, a Cerges is the superior reactor design.

 

[EmotionalFescue]

How difficult is it to tune the reactor with an opaque housing? I checked out filters and for some reason, the shipping seems to be very high, $25 for the lowest price shipping option. Due to this, I've been looking to amazon, and all of the clear housing I am finding seem to have lots of issues with leaking. The opaque housing appear to be stronger and more affordable I'm worried turning might be a challenge.

The only time I've used opaque it was when there was no tuning to be done (huge housing, small tank) because all of the water flow could push through the reactor without causing bubbles to escape.

I have used these housings in both 10 and 20 inch and they're good.

 

[Thenoob]

@Phil Edwards space shouldn't be issue. I've have the right side of the stand pretty much earmarked for the reactor since the co2 tank won't fit there and will have to sit external to the stand. In my head I was thinking a 10x2.5" housing since the tank is smaller and I've already obliterated my budget for this tank and need to start spending money on furniture not fishtanks . If the 4.5" housing is a necessity I should be able to make work, but not my preferred course of action.

@EmotionalFescue thank you, that helps put my mind at ease. Those were actually the housing I was reading about the leaking issues with. I suppose leaking is much less of an issue since the working pressure is so low in comparison to a house water line. When you ordered these housings, did they come with an o-ring? I've seen mixed information on weather they do or not. Not a problem to get one if it doesen't, just nice to know.

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[EmotionalFescue]

Right - our pressures are much less in this application and I guess that makes all the difference. My only suggestion is to use a LOT of thread tape on the ports, because those can drip a bit. I think I found like 12-13 wraps to be the sweet spot. Mine did come with the rings.

 

[Thenoob]

The housing and I picked up the needed fittings. However, I can't find the correct sized plastic hose barb to fit the co2 tubing (4mm ID, 6mm OD). I bought during the marine depot liquidation sale.

I'm thinking about just drilling an undersized hole (5 mm or so?) And pulling the tubing through. Yall think this would work okay?

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[EmotionalFescue]

I

The housing and I picked up the needed fittings. However, I can't find the correct sized plastic hose barb to fit the co2 tubing (4mm ID, 6mm OD). I bought during the marine depot liquidation sale.

I'm thinking about just drilling an undersized hole (5 mm or so?) And pulling the tubing through. Yall think this would work okay?

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I wouldn't try to go straight into the housing without a bulkhead.

If it's standard 1/4" OD tubing then you just need a 1/8" brass barb. Don't think vinyl would be strong enough in that small a diameter.

 

[Thenoob]

I was thinking of drilling into the pvc hard plumbing around the reactor. The tubing is 6mm OD, 4 mm ID co2 resistant so a bit larger then 1/8th on the ID. According to marine depot it fits 3/16" airstones and accessories. Do you think an 1/8" barb would work? Also, is there problems wirh copper or leaching for the brass barbs?

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[EmotionalFescue]

I was thinking of drilling into the pvc hard plumbing around the reactor. The tubing is 6mm OD, 4 mm ID co2 resistant so a bit larger then 1/8th on the ID. According to marine depot it fits 3/16" airstones and accessories. Do you think an 1/8" barb would work? Also, is there problems wirh copper or leaching for the brass barbs?

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I do think a 1/8" Barb will work. I wouldn't worry about leaching.

 

[Thenoob]

Got the reactor plumbed up but might need to redo it. I don't know why but front to back length never crossed my mind when I was doing the plumbing. As a result the plumbing is right at the edge if both the front and the back of the stand. Once the hose barbs are on it'll be even longer. I was trying to get fancy and avoid elbows on the mainline but will have to use them anyways if I have any chance of getting the current plumbing to work.

I do have some space to hang it out the back of the stand since the overflow box and drains already keep the stand off the wall. So I guess see how bad it looks once it's plumbed in.

On a side note, purple primer is the bane of my existence. I am in awe of the people who can plumb this stuff with out getting it everywhere.

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[EmotionalFescue]

Looks good!

You could slim it down by ditching the union and using a street on the input. You'd need to move the barb to a tee below the street fitting, but you've got room.

I don't use primer for reactors, fwiw. It's debatable (and widely debated among plumbers apparently) whether it achieves anything though it's required by code in most places.

At one point I found an interesting post in which a plumber described a pretty meticulous comparison of primed and umprimed joints for resistance to failure from different kinds of stress (compression, sheering, twisting, etc) and the unprimed joints held up better! His theory was that the primer weakens the PVC in order to create that liquifying reaction that allows for the weld. Sort of a robbing peter to pay Paul kind of deal I guess.

 

[Thenoob]

Looks good!

You could slim it down by ditching the union and using a street on the input. You'd need to move the barb to a tee below the street fitting, but you've got room.

I don't use primer for reactors, fwiw. It's debatable (and widely debated among plumbers apparently) whether it achieves anything though it's required by code in most places.

At one point I found an interesting post in which a plumber described a pretty meticulous comparison of primed and umprimed joints for resistance to failure from different kinds of stress (compression, sheering, twisting, etc) and the unprimed joints held up better! His theory was that the primer weakens the PVC in order to create that liquifying reaction that allows for the weld. Sort of a robbing peter to pay Paul kind of deal I guess.

The primer weakening the pvc seems like a very plausible theory to me. At one of my previous jobs, solvent weakening of polymers was something we had to watch for as part of our process control. Different polymer and solvent but same general principle I would think. I'll probably try not using the primer if I replumb the reactor.

Just want to make sure I'm on the same page as what you're suggesting. To slim it down I was thinking I could use street elbows on both sides, remove the union entirely, and use three-way elbows (like I have for the CO2 barb) instead of Tees for the mainline in and out.

The only thing that worries me about this plan, is that without a union its seems like you'd be out of luck if the threaded connections to housing leak. The union lets me unscrew the fittings after everything is cemented together if I have to. However, I might not have a choice on replumbing without a union as I'm worried that I didn't get the alignment on the sealing faces close enough to seal. I suppose I could use a heat gun to pull everything into alignment if I decide to stick with the current plumbing. Since heat poses a risk to the cemented joints, I'll consider that a non-preferred option.

 

[EmotionalFescue]

The primer weakening the pvc seems like a very plausible theory to me. At one of my previous jobs, solvent weakening of polymers was something we had to watch for as part of our process control. Different polymer and solvent but same general principle I would think. I'll probably try not using the primer if I replumb the reactor.

Just want to make sure I'm on the same page as what you're suggesting. To slim it down I was thinking I could use street elbows on both sides, remove the union entirely, and use three-way elbows (like I have for the CO2 barb) instead of Tees for the mainline in and out.

The only thing that worries me about this plan, is that without a union its seems like you'd be out of luck if the threaded connections to housing leak. The union lets me unscrew the fittings after everything is cemented together if I have to. However, I might not have a choice on replumbing without a union as I'm worried that I didn't get the alignment on the sealing faces close enough to seal. I suppose I could use a heat gun to pull everything into alignment if I decide to stick with the current plumbing. Since heat poses a risk to the cemented joints, I'll consider that a non-preferred option.

Yep - you're 100% correct that without a union you will not be able to retape the threads if it leaks. That's why I wrap the hell out of those threads! I think with ~15 wraps you'll be good on leaks.

 

[Thenoob]

I did end up sticking with the original plumbing with the union and seemed to fit in the stand all right. I was glad to have the union since I did end up with leaky threads despite lots of Teflon. I retaped with even more teflon and it seemed to have fixed it but I didn't get a chance to test it very long before I cracked the back panel of the tank while trying to correct a leak in the return bulkhead threads. Luckily I have a backup tank that I just need to drill and paint.

For the second version of the tank, I am thinking of not drilling the return since it I could not get it to stop leaking. Instead, I am planning to run the return over the top. In my head, I can see this return taking a few different forms.

Form 1: Use loc line Y and nozzles like in the original tank, just over the top now
Form 2: Spray bar
Form 3: Spray bar with Loc line Y in the center to also return water to the lower reaches of the tank.

If anyone has any thoughts let me know! I suspect the returns won't be hard to build so I might start with form 1 since its the simplest. If it isn't looking great I can then replace it with a different version.

 

[Phil Edwards]

Form 1: Use loc line Y and nozzles like in the original tank, just over the top now
Form 2: Spray bar
Form 3: Spray bar with Loc line Y in the center to also return water to the lower reaches of the tank.

Since you're using a sump and have an overflow, a spray bar running along the bottom is a great way to do a return; just make sure to drill an anti-siphon hole just above the water line. Some people prefer to have their spray bars near the top, which works just as well, but having the bar on the bottom has three advantages:

1. It's easier to hide a single down-draft tube than it is a big spray bar along the top.
2. The downdraft acts like an extra CO2 reactor for the fine bubbles.
3. Having the flow along the bottom helps flush debris from the base of the plants and knocks any old, dying, leaves off the stem bases.

If you want to get super-fancy, you can drill holes in the downdraft tube as well. You may need smaller holes if you do this to keep flow coming out of the whole assembly, but it can help to create circular flow in the tank as well. I used to have a big former reef tank that was drilled for outlets in the top and bottom corners of the back. I put spray bars on all four; two along the length of the bottom and two along the length of the sides. This was one of the best arrangements I've ever had and would 100% do it again.

I normally fill the tank until it starts draining into the sump, then fill the sump 100%, start the pump and mark the actual max-fill line on the sump and running high-water mark on the downdraft tube of the return. That's the point, or just slightly above that, where I'll drill a small 1/16 to 1/8 inch hole. This will break the siphon from the return when the pump's off. The other mark I make is 1-2 inches below the max-fill line in the sump; this is the actual max-fill. The extra inch or two will keep you from over-filling the sump and risking a flood when the pump's off. This makes it super easy to keep the sump topped-off for consistent water volume.

Hope this helps,
Phil

 

[Thenoob]

Build up a preliminary version of the return using the loc line. Besides being a simpler, it let's me put flow down near the bottom and up top. I might still switch it our for a bottom spray bar as @Phil Edwards suggested since that's probably the better design.

For now atleast this return seems to be working well. I do definetly notice a reduction in flow due to the double elbow. Running the pump at 100% does have everything moving pretty well but it's not ridiculous so hopefully I won't be wanting for more flow.

The tricky part about the locline was the siphon break, due to the design of T the hole had to go very close to the surface which means its giving me some surface ripple. I'm going to chose the look at that as a positive. For the hole, I went with 3/16th which was about as large as would fit. So far it seems to be working, and I can hear it sucking as the siphon breaks immediately after the pump stops.

The vinyl tubing I used to connect to the reactor is driving me nuts. It's so stiff it's very difficult to work with or position. I do plan to use pipe straps to fix the return in the place I want it and keep it straight after it passes leak testing.

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