Reservoir Size compared to system size

PLEASE HELP. Im building a 20 bucket RDWC system with 5 gallon buckets. If each bucket holds 2 1/2 gallons of H2O, how big does my reservoir need to be? Should my reservoir be another 5 gallon bucket or do I need 10, 20, 40, 50 gallons of reservoir? Im using a 1638 GPH inline water pump and a 1/4 HP water chiller. Deeply appreciate any and all comments. Thanks and PEACE...…………...

JesusWasaMyth said:

PLEASE HELP. Im building a 20 bucket RDWC system with 5 gallon buckets. If each bucket holds 2 1/2 gallons of H2O, how big does my reservoir need to be? Should my reservoir be another 5 gallon bucket or do I need 10, 20, 40, 50 gallons of reservoir? Im using a 1638 GPH inline water pump and a 1/4 HP water chiller. Deeply appreciate any and all comments. Thanks and PEACE...…………...

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the more water volume, the more stable the pH will be. and less res changes.
and just remember the water level in your control will be the water level in the buckets too.

rkymtnman said:

the more water volume, the more stable the pH will be. and less res changes.
and just remember the water level in your control will be the water level in the buckets too.

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Precisely.

I like to do as large as possible within reason due to those factors. Changing less often and checking less often is one of the main reasons to go hydro over top feed soil / coco.

Renfro said:

Precisely.

I like to do as large as possible within reason due to those factors. Changing less often and checking less often is one of the main reasons to go hydro over top feed soil / coco.

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true true i let my dwc run for 2 weeks sometimes with zero ill effects and still good growth do that with coco they would be dead

rob333 said:

true true i let my dwc run for 2 weeks sometimes with zero ill effects and still good growth do that with coco they would be dead

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With flood and drain I run my reservoir with only top offs / add backs for the whole flowering cycle without any issues. Major savings on nutes and filtered water.

Renfro said:

With flood and drain I run my reservoir with only top offs / add backs for the whole flowering cycle without any issues. Major savings on nutes and filtered water.

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This is what I have been doing with no ill effects noticed. 55 gal tank with ~30-40 gallons of solution at a time. I just let em drink it down and add back 5-10 gallons depending on what the ppm looks like.

sandman83 said:

This is what I have been doing with no ill effects noticed. 55 gal tank with ~30-40 gallons of solution at a time. I just let em drink it down and add back 5-10 gallons depending on what the ppm looks like.

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My flood and drain res is auto topped off by the RO filter via a float valve and solenoid valve on a timer. This tops it off once a day when the lights are off and all the water is guaranteed to be back in the reservoir from the tray. All I have to do is give the pH and PPM a weekly check. After the first 2 - 3 days the pH rarely needs to be touched with the RO. If the PPM is a little low I just calculate what nutrient add back is required. Generally in flower my add backs are mostly just the GH Bloom.

rkymtnman said:

the more water volume, the more stable the pH will be. and less res changes.
and just remember the water level in your control will be the water level in the buckets too.

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Thank you very much... It makes sense now that I understand the concept.

Renfro said:

With flood and drain I run my reservoir with only top offs / add backs for the whole flowering cycle without any issues. Major savings on nutes and filtered water.

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You can run a whole flower cycle with just topping off your Reservoir and replacing Nutes as needed?

JesusWasaMyth said:

You can run a whole flower cycle with just topping off your Reservoir and replacing Nutes as needed?

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Absolutely. I did it on a large scale for a very long time in multiple grows. I had 300 gallons for each pair of 4x8 trays. I was running lucas formula back then and for each 1kW light I was adding 15 mL of micro and 30 mL of bloom daily to maintain the 1000 PPM target. If I missed a several days of add backs it wasn't a big deal at all as it was a very small PPM drop. I usually just serviced them once a week with a 100/200 add back.

JesusWasaMyth said:

Thank you very much... It makes sense now that I understand the concept.

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JesusWasaMyth said:

You can run a whole flower cycle with just topping off your Reservoir and replacing Nutes as needed?

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You have the right people helping you here. I'm not running hydro now, but I listen close to everything both these guys say.

Renfro said:

With flood and drain I run my reservoir with only top offs / add backs for the whole flowering cycle without any issues. Major savings on nutes and filtered water.

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my last grow i did top off thru out whole veg and flower lol i no what u mean this run i really wanted to see the diff so far none

rob333 said:

my last grow i did top off thru out whole veg and flower lol i no what u mean this run i really wanted to see the diff so far none

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from a dump every week to not they still lokk happy as sorry i dumped at week 4 in veg last run and did a full cycle in flower tho of top off

My opinion is an echo... The bigger the better and more stable. Of course with diminished returns. I like a res double the volume of my sites. Find it's does the job for me.

You want a turnover of about 10x per hr of the total volume of sites. I find it's closer to 3 gal a site. Although as little as 4x can work on a smaller system.

A good rule of thumb if you keep your nutes dialed in is to do a res change once the volume of add back equal the system volume. This will prevent nutrient ratios from becoming to far out and causing issues.