Recirculating Ebb & Flow 💦

It’s been a while since I have posted an update on my big room so I thought I’d start a new thread detailing the changes I’ve made since the HPA setup was torn down.

To catch up you can read my previous build thread here.

Since the wife started growing in the tent I didn’t feel pressured to get the big room running again, and I was able to take my time and make sure everything was setup exactly how I wanted it.

System Overview

Recirculating ebb & flow, with water depth and timing controlled by a loop siphon
8x 10 gallon medical planters from The Bucket Company
1585GPH external water pump
35 gallon reservoir
Glycol reservoir w/ Active Aqua 1/10 HP chiller and aquarium heater


The DC pump is plumbed directly to the tank outlet and then splits off. One section goes through the wall and feeds the system while the other is passed through a valve and then angled down towards the bottom of the res. Even though the pump has 10 settings the valve gives me finer control of the flow going into the system and the return pipe works to flume the water and keep things stirred up. I will be adding a venturi aerator to this secion in hopes that I can eliminate the air pump entirely.

The section that comes through the wall then passes through the two in-line filters before heading off to feed the grow beds. Also note that there are strategically-placed unions all through the supply run. This was done so that everything can be disassembled and cleaned w/o cutting a single piece of PVC. The union on the left of the next picture also allows me to change the entire supply rail if I wanted to reduce the number of grow beds.

Here’s a view looking down the supply manifold. The main line is 1" PVC that then goes to a 3/4" reducing tee before hitting the union valve on each grow bed. The spray manifolds that come w/ the system are great and will give even water coverage from above.

From above you get a good idea of the layout. Each pair of grow beds has an HLG300 mounted above them and their placement gives me a small overlap at the edges while allowing each plant to have a 3x3 space to grow in.

One nice feature of The Bucket Company is that each grow bed has a nylon bag that goes into it. This allows me to keep the medium separate without having to worry about it plugging up the drains. I went ahead and picked up the hydroton I would need to fill these. (Not looking forward to washing and pre-soaking all of this.)

Today and tomorrow I’ll be finishing up the return lines and doing initial testing of the siphon. I’ll also try and take some updated photos of the glycol reservoir.

I also do other updates over on IG @

Or you can follow along with the wifey’s grow tent @

Really excited to get this build wrapped up and get plants back into the system.


I had forgotten you were into siphons too!!

Very cool. Cant wait to see details on the siphon setup.

As usual, your workmanship is just outstanding - which would normally mean I hate you, but you do siphons, so I forgive you :wink:

The only thing I would have tried to change is to leave a walkway between the tubs. Three feet of reach is a back breaker for me when I am working on the plants.


Well f*** me. I don’t want to show you mine. Same idea but lower budget for sure.


I’ll post some pics tomorrow as I get into further testing. :slight_smile:

Thank you sir, I took my time with this and so far it’s really paid off.

Thankfully I have long arms. :slight_smile: I do have a rolling stool for working from below and a small 4 step ladder for reaching over the top. Hopefully that’s enough.

Everyone starts some place man. The proof of concept for this system was put together for around $100 and produced quite a bit of bud from a single plant.


I completed the return lines tonight, including cutting what I hope is the last hole in the wall.

I filled up the res with some hose water to do my testing and check for leaks. Thankfully there were none and I was able to really see what this pump could do. There are 10 speed settings so I started with level 1, at this rate my bypass valve works perfectly for redirecting the flow away from the grow beds. Playing around I took the pump to level 10 – and holy shit, this thing can move some water. Even with my bypass fully open the grow beds were getting a ton of water directed at them. The pump is also totally silent even when turned all the way up.

Unfortunately the res does not hold enough water to fully test the system until I get media in the grow beds. I did test the siphon manually a few times and it looks like it should move plenty of water to drain the tubs. Now I just need to get the hydroton washed and then I can dial in the incoming flow.

I’ll take pictures tomorrow, time for bed now.


Ya close. This is my single GSC without net and plenty of LITFA.


Very nice and very clean build! I’ll be following!


Everything looks so clean and new! Great setup! I had a couple dumb questions if you don’t mind

When running the syphons, do you run the pump so the time?

I’m assuming the the buckets are higher than the res?

Thanks. Look forward to seeing that room with some green in it!


The pump runs 24/7. The siphon controls the ebb and flow timing, but requires a constant water flow. If the incoming flow stops it will stay at the same level forever.

No, they’re on the same level. The siphon height controls the high water mark in the grow beds but the siphon effect allows water to flow uphill once the back pressure is high enough. This gets me up and into the res w/o the need for a return pump.

It will make more sense once I get a few more photos tonight. Just washing a ton of hydroton now… :slight_smile:


If you are curious about siphons, try Googling Bell Siphon or Loop Siphon. There are tons of YouTube videos on siphons. There are many different types depending on what you are trying to do. They are surprisingly common in commercial grows - at least I had no clue until I did the research. I think siphons are cool :slight_smile:


I researched them years ago looking into aquaponics. I had seen allot of big scale stuff in greenhouse beds, but not allot on on smaller grow room scale.
I really like working with hydroton with two exceptions. Washing and I hate walking on the inevitable stray ball with my bare feet! Lol


I got my hydropon8c running :+1:

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Last weekend I washed 200L of hydroton and filled the grow beds only to realize I needed another 100L to really fill them where I wanted. Sent the wife back to the hydro store while she was in town and get all of that sorted. We now have totally filled beds and they’re cycling now to get any remaining contaminants out and balance the pH of the media.

The secondary filter is almost mesmerizing to watch. It also ended up being one of the best pieces I added to the system. I can slide a 5 gallon bucket under it, turn the dial and it instantly flushes the filter. If needed I can hook a drain hose to the bottom and run it outside, so I can use the main pump to drain the res. In the future this will be plumbed directly up to the drain in the room to make res changes a breeze.

I’ve spent the past two days playing with different siphon setups and trying to dial in the ebb and flow. So far I’m having a lot less luck than I did previously and I suspect that the 3/4" tubing just doesn’t work as well as the 1 1/4" drains I used to use. I have a few more ideas to play with before I change the return up entirely… Tomorrow I’ll hit the hardware store and pick up some more fittings to convert from 3/4" tubing to PVC.

First I’ll try a PVC U-siphon to see if that makes it more reliable. I might also feed two 3/4" hoses into a single 1" PVC manifold to increase the outgoing flow. (Even when siphoning it doesn’t seem as strong as I’d like it.)

I suspect that my geometry is off a bit, so it’s possible I just won’t get the siphon to fire like I want. If that’s the case I have one final backup plan – a control bucket type setup.

I picked up a dual float plug and another in-line pump. This should allow me to construct a float-based trigger that turns on and off the return pump while also keeping things small and compact.

I could buy a prebuilt control bucket but most of those run on a timer setup and I’d prefer to run my incoming flow 24/7, plus I’m limited on space to put this in the res chamber. I already have a return that goes back into the res that can be repurposed as the overflow, so that will eliminate any potential overflows from float/return pump failure.

Quite a few projects going on around here this weekend and the Amazon parts won’t arrive til Monday, but I will make progress one way or another…


What I found most critical as far as reliable tripping of the siphon, was the fill rate. If the fill rate was too slow, the siphon would sometimes get stuck in trickle mode and never fully trip.

In that case, the key to fixing it was the drain side of the siphon. I had to use either a taller vertical part of the drain line - or - a longer horizontal leg in the outflow. It surprised me that the horizontal portion of the drain line had more effect as far as reliable tripping.

The other thing that helped when I was doing loop siphons was to use a sharp pointed “loop” instead of a curved or flat topped loop. It also helped a lot to use a trip vent (I think thats what it was called). I’ll see if I can find some pics…


I miss spoke above - I had some trouble with the siphons tripping initially, it was more of a problem that they wouldnt stop when the water level got down to the lower cutoff. If thats happening, adding a vent line fixes that.

I tried all of these variations. The one on the far right worked best.

You can see the small very tube. That vent fixes the issues where the siphon never really stops and re-sets. Water keeps trickling out unless you can break the vacuum that gets created in the trapped air at the top of the loop. When the water level gets down below the bttom of the vent line, air can enter and fill the top of the loop - which breaks the siphon action completely.

If they wont trip at the start, then you need more vertical drop or add a longer horizontal leg after the drop. Some people also recommended adding a P trap in the drain, but I never saw any improvement with the p trap.


It occurs to me that there is a good chance you already know all this since you said you had used siphons before - sorry!

On the off chance you didnt know - one more point :wink:

All the siphon specific problems I had - which prompted the solutions above - were from trying to slow down the fill/drain rate. In particular, I wanted to slow down the fill rate. The reason being to give the roots more “dry” time.

You have much higher flow rates in a much larger system, so none of these things may apply. At hi flow rates, the siphons work much more reliably, but that means shorter cycles.


No worries, this is all good info man, appreciate it! Unfortunately my problem is very different.

The main issue was caused by my drain line being 3/4" flexible PVC hose, and not standard pipe. This meant I could not reduce the size of the loop w/o causing kinks and forced too many “smooth transitions” which didn’t really allow the siphon to fire properly. (No good way to stack the water up for the fall to kick it off.)

I just got back from a run to the hardware store and I picked up a number of random parts I was missing. The main thing is I now have the pieces I need to convert from the flex hose to normal PVC. This will allow me to go back to using hard lines for the siphon, meaning I can once again get the hard bends I need for it to properly start.

Thankfully this setup was also designed knowing that siphons required me to be able to adjust the in and out flows – besides the pump control (1-10) I also have the valve on the supply-side to control flow. On the outflow I also have a valve that can be adjusted, as needed. The parts I picked up also mean I can run two return lines (4 beds per) and join them at the PVC for even better flow if that becomes an issue.

Last resort I have the floats/pump coming tomorrow so I can use that to pump when full, while still keeping the overflow in place just in case of any failures. (No overflows, while still keeping water flowing.)

I’ve also started taking footage of the entire setup from start to finish. Going to do a detailed breakdown on YT, there’s just too many cool little things in this system to not share. :slight_smile:


I’m looking forward to this. You are doing some very interesting things here.


Reworked everything last night and I’m still having the issue with not enough incoming flow to kick off the siphon. It really looks like it wants to start, but the flow just isn’t there.

I tested turning up the supply all the way and the buckets fill really quickly, but once it reaches the siphon I get the same result. The buckets continue to fill while the siphon struggles to start. This confirms my suspicion that there is just too much restriction in the 3/4" return lines for the 3/4" PVC siphon.

Here’s the what the siphon going back into the res looks like today. The other half of the diamond is inside of the res itself.

Here you can see how I have each run of 4 buckets joining into a tee, then making a 90 degree turn to the valve that leads to the siphon.

Between the 90 degree turn, the small diameter of the tubing, and the lack of flow at the siphon I truly believe this is where my problem lies.

Today I am going to make one final change that I am hoping will increase the return flow. Using a few spare parts and repurposing some of what I already have in place I am going to build this mini-manifold.

Both sides will take a 3/4" tube in and will feed into a single 3/4" PVC that will go vertical to the siphon. I will then eliminate the return line tee entirely and run a secondary hose back to the manifold. This should double the amount of water that is able to go into the siphon and should (hopefully) allow me to trigger the siphon reliably.

If this fails then I can always rebuild the siphon using 1/2" PVC which will require less water to start, but will reduce my output flow capabilities.

Of course, there’s also the possibility that I just don’t have enough water pressure above the siphon to trip the system and I could be fighting a losing battle here. Either way I am only going to play with this a few more days before I give in and use the recirculating timer.


Im not 100% clear on the setup.

In the first pic - is that white container on the right the rez or a control bucket?

Is the siphon draining INTO or OUT of the rez/control in that pic?

Note: you will get better flow rate if you eliminate that 90 deg ell on the left side. Replace it with a 45 and just go straight down. That extra kink created by the 90/45 combo just adds resistance to the flow. Doing that is only needed if you are forced to have the drain and fill lines close to gether.

Picture #2 - is it the black line that is the siphon return or the white 1" PVC?

Im not getting a clear pic in my mind of exactly how this is all plumbed.

I assume the pump goes from the rez to a manifold that fills all the buckets at the same time? Those are all rigid PVC pipes? And the drains are all flexible black hose?

I had this exact same problem. The cause is two fold. The main issue is that the water level in the buckets raises too slowly. This keeps the flow rate too low initially when the siphon is trying to start.

Dont think in terms of water flow in GPM. Think in terms of inches per second of water level rise at the siphon peak.

Whats happening is the water level is going up at the siphon at a certain rate depending on the water flow from your pump. As the water level gets up to the top of the siphon, water begins to drain out. As soon as the water starts to flow over the top of the siphon, the water level will go up even slower. If the water level is not going up fast enough, the siphon may never have enough flow to suck all the air out of the top of the siphon. Its that trapped air that is the problem.

If you are stuck with a slow water rise level - cant turn the pump up any more or what ever, then you need to increase the vertical drop in the outflow side of the siphon and/or add a horizontal leg on the down side. Either option will help suck out the air. The other option is to try the vent line I mentioned above. That vent also sucks water into the top of the siphon early in the cycle and helps get the trapped air out. Then is helps break the flow at the end.

I think the single most important thing you can do is fill the buckets faster. I wanted my fill rate as slow as possible to allow for more dry time on the roots, but there are limits to the siphons ability to work slowly.

You might also try feeding two fill pipes into a single drain pipe on the siphon. Look at the ‘T’ siphon but modify it so you have the minimum amount of trapped air at the top.

Again, the trick is getting that trapped air OUT durring the initial slow filling of the siphon.