Reservoir size relative to number of plants

[Ruckatruck]

Is there a formula for determining the optimum size reservoir for the number of plants? As I purge my reservoir every week and put in fresh nutes, I wonder, "Am I trowing away good, unused nutrients? Could I use less water, and therefore smaller quantities of nutrients, and achieve the same results?" After all, those nutes aren't cheap. I use a 12 gallon reservoir and am set up to grow 11 plants in my system. Could I use 10 gallons, or 8? Anybody got an answer?

 

[HashAssassin]

What system are you using? Most res sizes are based are based on how much liquid you need to keep the pump wet while filling the system. I only change my nutes every 2-3 weeks but have gone longer depending on what phase/system I am in at the time. Also, what recipe are you using for your nutes? I usually use about half the recommended dosage but sometimes less.

 

[dogstick]

I think a good rule of thumb is 3-5 gallons per plant. I have read 5 is what you are reaching for.

 

[HashAssassin]

I think a good rule of thumb is 3-5 gallons per plant. I have read 5 is what you are reaching for.

It's system dependent. If the 12 gal res works for your setup stick with it.

I've done aeroponic systems with 36 plants and single plant dwc systems with the same 18 gal res. Both systems produced great plants. Using your 5 gal theory I would have needed an 180 gal res!! That would have been bigger than my whole garden.

Ruckatruck...

Are you actually mixing up 12 gal or just 10 gal? i.e. for my 18 gal res I mix up 15 gal of nutes and 25 gal of nutes for my 27 gal res. What are the ppm's for your current nute soup?

 

[Wingman420]

I use a 189ltr (50gal) res for three 3'x3' ebb and flow tables because as @HashAssassin stated the pump must stay "wet" to recirculate the water. Ideally one wants to push as much oxygen rich nutrient solution through the root system in the "flood" stage as possible.
The plants uptake some water each time so a larger res allows freedom from having to "service" the res daily. All large greenhouses are made to recapture and re-use all old nutrients by Law and instead of throwing ferts away use them in drain to waste applications. This must be done with liquid not loaded with salts so care is taken to minimize salt buildup in all systems.

 

[Ruckatruck]

Thanks for the info and questions. Here are the answers:

My system consists of three 42" long PVC 5" square fence posts, sealed at one end, the other with drain pipes to the Rubbermaid Roughneck reservoir, which probably holds 16-18 gallons of water full. I use 12 gallons. The two fence post sections on the outside have spaces for 4 plants each, and the one in the middle has spaces for three. These are cut-outs for three-inch net pots. It's a little tighter than the 12" generally recommended, but I am growing a Sativa strain that grows tall with thin leaves. Depending on the results of my current grow, I may reduce to eight plants next time -- just the two outside sections. Plants are fed via quarter-inch tubing and small spray heads between each plant and at the ends.

I cycle my pump (1050 gph) 5 minutes on, 10 minutes off. That timing is totally arbitrary -- I have no idea what the ideal would be, or if there even is one.

As for nutes, I am currently using Advanced Nutrients exclusively. I use the concentrations recommended on their online nutrient calculator, only about 20% less, as I have read elsewhere that the strain I am growing (Kali Mist) does better with lighter applications. I use Sensi Grow and Bloom, A and B (not at the same time, of course), Voodoo Juice, B-52, Big Bud, Overdrive, and will flush with Final Phase. I kept the same nutrient solution for the first two weeks, when they were small, but they grew quickly -- they were 8 to 14 inches tall -- and I changed to the bloom nutrient solution. I change the solution weekly, topping off during the week with water as needed (sometimes as much as a gallon a day) and adjusting the ph (5.6 ideally, I'll take anything within a couple of tenths).

The plants are beautiful. Perhaps I'll post a grow log someday.

Ruckatruck

 

[dogstick]

It's system dependent. If the 12 gal res works for your setup stick with it.

I've done aeroponic systems with 36 plants and single plant dwc systems with the same 18 gal res. Both systems produced great plants. Using your 5 gal theory I would have needed an 180 gal res!! That would have been bigger than my whole garden.

Ruckatruck...

Are you actually mixing up 12 gal or just 10 gal? i.e. for my 18 gal res I mix up 15 gal of nutes and 25 gal of nutes for my 27 gal res. What are the ppm's for your current nute soup?

I have used an aeroflo 30 with 20 gallon res and have burned a pump because it can suck up the res so quickly. You must really have to keep an eye on 36 plants with only a 18 gallon res

 

[HashAssassin]

I have used an aeroflo 30 with 20 gallon res and have burned a pump because it can suck up the res so quickly. You must really have to keep an eye on 36 plants with only a 18 gallon res

I used a cycle timer but I also checked on the system every day. Used to sit in that room and read in the winter...excellent light therapy.

 

[dogstick]

Hash, Did you think you had enough root room in your aero?

 

[mcloadie]

I wanna top feed 12 plants, 6 each in 3x3' trays....so as long as the pump doesn't go dry during the drip cycle I'm cool? And what I'm hearing is that the smaller the res is it will increase maintenance? And the size of the res will also increase the difficulty to either cool or heat the res? I'm going to use the grodan croutons for medium.

 

[dogstick]

When I talk about root room, i actually mean room. I have run 5 plants in a 20 gallon rez and the roots stuffed it completely so flushing it was way hard. I changed my res at least 10+ times with water and florakleen and it did not flush anything cause the roots did not allow any room for the water to exchange. yup larger rez easier to keep downthe temps and more plants less water will mean your ph, ppms will be harder to keep in check, meaning more swinging.

 

[jsudia32]

What system are you using? Most res sizes are based are based on how much liquid you need to keep the pump wet while filling the system. I only change my nutes every 2-3 weeks but have gone longer depending on what phase/system I am in at the time. Also, what recipe are you using for your nutes? I usually use about half the recommended dosage but sometimes less.

For 32 plants what would you recommend for the reservoir size for DWC hydroponics system?

 

[Delps8]

For 32 plants what would you recommend for the reservoir size for DWC hydroponics system?

This is a really old thread so you might not get many replies.

A couple of thoughts…

You might want to post this question in the grow room setup section. When you post your question in grow room setup, post some background information such as where you're located, why you're growing (personal, commercial, etc), your grow experience, and your budget. Without that, there's no way to give an answer.

Also, when you say "reservoir size" that leaves the impression that you're thinking you'll have all of your plants in one res. If that's the case, I'll chime in here and tell you that you do not want to do that.

On the other hand, is the case that you have a DWC system for which you want a reservoir?

if you provide more background info, the good folks here should be able to help.