I am running multiple 5 gallon buckets off a single reservoir. 1 plant per bucket.
Is there a rule of thumb for the flowrate through each bucket?
6 Likes
The system should recirculate 9 times per hour, give or take… I use 15 times per hour or rather the pump is rated 15 times the system water volume. Not exactly what you asked, but it’s what I got 
4 Likes
I just winged it on that one when deciding what to get lol but I have a 1000 GPH pump for my ~60-gallon system and it seems to work pretty good.
5 Likes
you want your pump to pull fast enough enough to move all the water in your system every 3.5-4 minutes. i would also advise putting a choke valve on your intake to help you even out water levels in each site
2 Likes
I run a 3500 lph pump on my 150 litre system along with a hailea v60 air pump that pushes 60l of air per minute through the coke can air stones. The water movement is immense and the plants seem to love it.
2 Likes
I imagine having a super sized pump and fast moving water would serve to oxygenate better?
3 Likes
it would, but it would also result in an overflowing control bucket, or at least very uneven water levels which could have a number of other undesirable results. balance is key with rdwc. too fast is bad, too slow is bad. both will kill your plants somehow, some way. max o2 potential in an rdwc is achieved (imo at least) by an appropriately sized pump with the return line set up as waterfalls to each site. you could run air stones too if you wanted but its kind of a hat on a hat with a waterfall setup
2 Likes
Interesting. Thanks for the info.
1 Like
Not in my case. Water levels are perfectly fine although I do admit I push the water into each bucket through a central line rather than pulling it into the control bucket. 
Yes. I do worry sometimes that the water movement being so strong that it will damage the roots but up till now for the past 10 grows or so it’s not been an issue
1 Like
Good to know. I’m hardly an expert on these matters and was just curious
1 Like
I figured I’d throw as much air into the water as I can. When water sits still and is starved of oxygen is when bacteria becomes an issue.
1 Like
I have way more air going into my bubble cloner than I need just because I have a massive air pump and I can.
1 Like
Yeah. Having a nice flow through each site will break surface tension and help o2 levels. This combined with a waterfall in the control bucket would allow you to remove the air pump completely…
One of the advantages of rdwc over dwc is water volume. The bigger the volume of water, the harder it is to destabilize it. Recirculating keeps each site ph/ppm identical to the next.
3 Likes
I use a 550 gph water pump I use inline so it doesnt heat the rez.
793 air pump.
The water goes back to the rez with a waterfall to add more oxygen. A valve also on the return to equalize the water levels.
3 Likes
My goal was to saturate as much O2 into the water as physics will allow at 68 degrees F. Borrowed experience from aquariums.
I rather oversized the air pumps and stones to that end. 2 coke can bubblers in each 5 gall bucket, and 4 tall coke can bubblers in the reservoir.
My original question was just trying make sure my sump pump was sized appropriately.
1 Like
What he said, ^^^^^^^^ 
Changes in water chemistry happen much slower in larger volumes of water.
A 100g saltwater fish tank is magnitudes easier to maintain than 20g saltwater tank!
4 Likes
ANY water circulation should be enough. I don’t think it matters how much or how fast the under current is moving. I’d be concentrating more on injection of air into the solution.
Obviously the faster the solution is moving around the system the faster the nutrient solution will stabilise so each bucket ppm level will be the same. Only reason I bought such a big submersible pump is the price was cheap and bigger in my eyes at least is always better 
2 Likes
Overkill is underrated 
But yknow, once you take into consideration the diameter of the pipes and all the obstacles water has to go through oftentimes its not even overkill but just right.
4 Likes