ebb and flow reservoir size

i ordered everything i need for my new ebb and flow setup a few days ago. should be here monday.


my flood tray is 19"x19" and 6"deep and made of steel. i'm am planning on filling it up with hydroton and putting the plants directly in it, no rockwool. i might use 3" net cups for support if they can't hold themselves up.

but anyways how big should my reservoir be? would ten gallons be enough? i'm planning on having up to 5 plants in the tray

10 gallons sounds just about right. actually, test with a 5 gallon bucket first, might be ok. I ran a temporary e&F system at about those dimensions and my 5 gallon pail was great.

Ok, i would much rather use a 5 gallon bucket.

my flood tray is 19"x19" and 6"deep and made of steel.

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I hope that's stainless steel you're talking about, otherwise you're going to need a plastic liner of some sort. The nutrient salts will react with regular steel, and cause it to corrode and rust. Not only that but your nutrient mix will get all messed up because of all the ions bonding with the steel, thus degrading the nutrient. All hydroponic parts, trays, plumbing, etc. (anything with water contact) have to be made of plastic or some other inert material.

In regards to what size res you'll need, there is an equation for that:

Length(cm) X Width(cm) X Height(cm) = Volume(cu.cm.)

So you've got 19"x19"x6", however, you obviously aren't going to be flooding to the top, so 4" is probably where you'll flood to.

....So 48.26cm X 48.26cm X 10.16cm = 23662.92 cubic cm = {convert to liters by dividing by 1000) = 23.7 liters {convert to gallons by dividing by 3.78} = 6.27 gallons

So you'll need 6.27 gal of solution to flood to 4" height

yes its stainless, its a bin from one of those commercial sinks you see in restaurants. you think i will have problems?

thanks for the equation, i've been trying to find one. i will probably get a 10 gallon tote and fill it up with 8 gallons

Also If you pack the table with other objects you can save some gallons. I got that equaion off bghydros website too. They got lots of ebb and flow help. I ran a table and used an eighteen gallon rubber,aid as the res. Cheap and durable, they work great. Also the botanicare ebb and flow fittings are nice to buy for like 10 bucks with shipping. They can turn anything into a pro table.

i'm planning on filling the tray with just hydroton. yeah i got one of those fittings but its from sunleaves. heres what i ordered from cheaphydroponics.com

General Hydroponics FloraBloom - Qt 1 $8.50
General Hydroponics FloraGro - Qt 1 $8.50
General Hydroponics FloraMicro - Qt 1 $13.50
General Hydroponics Liquid KoolBloom - Qt 1 $15.00
Sunleaves DuraPump H20 - 185GPH 1 $13.00
1/2" Barbed Elbows - 5pk 1 $3.00
Sunleaves Fill & Drain Kit 1/2 1 $7.00
Sunleaves Soft Black Tubing 1/2" - 25Ft $10.00
1/2" Barbed Tees - 5pk 1 $3.00
GH pH Control Kit 1 $12.75
Bluelab Truncheon Meter - PPM/TDS, CF, EC 1 $110.00
Nutrient Syringe 60cc / 2oz 1 $2.35
General Hydroponics 1/2" Grommet 8 $5.60
Hydroton Grow Rocks - 10l 2 $17.00
3" Net Pot 8 $2.80
Kord Square Pot 4" 8 $2.40

ForcedInduction said:

i'm planning on filling the tray with just hydroton. yeah i got one of those fittings but its from sunleaves. heres what i ordered from cheaphydroponics.com

General Hydroponics FloraBloom - Qt 1 $8.50
General Hydroponics FloraGro - Qt 1 $8.50
General Hydroponics FloraMicro - Qt 1 $13.50
General Hydroponics Liquid KoolBloom - Qt 1 $15.00
Sunleaves DuraPump H20 - 185GPH 1 $13.00
1/2" Barbed Elbows - 5pk 1 $3.00
Sunleaves Fill & Drain Kit 1/2 1 $7.00
Sunleaves Soft Black Tubing 1/2" - 25Ft $10.00
1/2" Barbed Tees - 5pk 1 $3.00
GH pH Control Kit 1 $12.75
Bluelab Truncheon Meter - PPM/TDS, CF, EC 1 $110.00
Nutrient Syringe 60cc / 2oz 1 $2.35
General Hydroponics 1/2" Grommet 8 $5.60
Hydroton Grow Rocks - 10l 2 $17.00
3" Net Pot 8 $2.80
Kord Square Pot 4" 8 $2.40

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Do I see 10L of hydroton on this list? That ain't going to do it for that size tray. You are going to need more like 50l of hydroton at least. I have a 3x3 and it took me 2 large bags >100l of hydroton to fill it up. I personally wouldn't use even a stainless steel tray.

i got 2 10l bags. i guess i'm gonna give the stainless a shot, because the tray is the perfect size and it was free

The bigger the res the more stable it is...

The more stable your res... the better off your plants will be..

I say any less than 20 gal and you are asking for pH and PPM nightmares...

BUT... go with what you know...

GypsyBush said:

The bigger the res the more stable it is...

The more stable your res... the better off your plants will be..

I say any less than 20 gal and you are asking for pH and PPM nightmares...

BUT... go with what you know...

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i would love to have 20 gal, but i dont really have the room.. it can't be more than 14 inches wide so i need something tall and skinny

By that same equation, you can figure out how much hydroton you'll need as well. You've got 20l of hydroton and to fill your tray to 4" height is 23.7 liters of volume. So you should be able to fill your tray to around 3.5" with hydroton, that should be plenty. You could also fill up pots and do it that way, but you should be fine doing it either way. You also have to take into account that all that hydroton is taking up volume that water would otherwise take, so you probably will only need a 5 gal res to fill that up. You won't know for sure until you've got everything set up. Just for ease of use and future proofing, I would use a rubbermaid tote (15 gal) and just fill it up half way.

Just speaking from personal experience...

Get the biggest res you can possibly fit... walmart has plastic containers of just about every size...

i guess i should have ordered more! oh well next time. 3.5 should be fine, i might even do 3" so i can have a little extra to fill a couple 3" net pots to do dwc on the side.

gypsy, i'm gonna go as big as possible! no walmart around here but i've been to kmart and home depot a couple times looking at different sizes, i can't find anything tall and skinny..

maybe i could connect 2 5 gal buckets together and have a dual reservoir? how would i do that? or maybe 2 10 gal totes?

I wouldn't agree that bigger is better when it comes to the reservoir. If you run into problem you have to to flush that big ass reservoir. That means flushing and wasting more nutes. You are going to adjust PH every day anyway with all that hydroton and I wouldn't expect a larger reservoir to do much good. If you're a good diligent grower you're going to be flushing that res. every two weeks anyway and flushing a ton of nutes down the toilet is a bitch.

Get an appropriately sized reservoir and things will be cheaper for you. That being said, I agree that 5 gallons isn't likely to be large enough. 10 gallons sounds about right to me.

Office/kitchen trash cans are usually tall and skinny..

Hell... get some bits of wood, make a frame and throw some pond liner over it...

Go with what you know bro...

But I have been there and small reservoirs are nothing but trouble...

The plants drink the fast, the ppm shoots up the ph shoots up...

Then you're chasing them all over the place... everyday...



To small a res and the plants will drink the water faster than they use the nutes... so the PPM climbs...

To big a res and the plants use the nutes faster than they drink water, causing the PPM to decrease...

The correct size res will maintain a balance... the plants will consume the nutes at the same rate as they intake water... maintaining a stable solution...



Reservoir stability is very important.. the plants do not like shifting pH and PPM....

GypsyBush said:

Office/kitchen trash cans are usually tall and skinny..

Hell... get some bits of wood, make a frame and throw some pond liner over it...

Go with what you know bro...

But I have been there and small reservoirs are nothing but trouble...

The plants drink the fast, the ppm shoots up the ph shoots up...

Then you're chasing them all over the place... everyday...



To small a res and the plants will drink the water faster than they use the nutes... so the PPM climbs...

To big a res and the plants use the nutes faster than they drink water, causing the PPM to decrease...

The correct size res will maintain a balance... the plants will consume the nutes at the same rate as they intake water... maintaining a stable solution...



Reservoir stability is very important.. the plants do not like shifting pH and PPM....

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The ratio of how much ppm the plants drink to water really only relates to how hungry the plants are versus how thirsty they are. If your PPM is rising in your reservoir you have too strong of a nute solution. If it's dropping then it's not strong enough. Not directly related to reservoir size at all.

laserbrn said:

I wouldn't agree that bigger is better when it comes to the reservoir.

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based on what?

If you run into problem you have to to flush that big ass reservoir. That means flushing and wasting more nutes.

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What kind of problem causes you to flush?

I have never had to do it...

You are going to adjust PH every day anyway with all that hydroton and I wouldn't expect a larger reservoir to do much good.

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Bollocks...!

My pH stays stable for well over a week... 5.7~6.2 pH

If you're a good diligent grower you're going to be flushing that res. every two weeks anyway and flushing a ton of nutes down the toilet is a bitch.

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I agree that a bigger res requires more nutes...

But I do not use a ton... at all... in fact I use about $40 a month worth of nutes to get an Oz a day...

That is not very much in my book... deff. not a waste...

Get an appropriately sized reservoir and things will be cheaper for you.

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Maybe I use the "bigger the better" term loosely, knowing that people will only have so much room... and that they will end up using something small...

I agree with what you said...

but chances are that the right size res is bigger than they were going to use anyways...

Take more as a "forum slang" to get a point across than a hard "get a one million gallon res for your 1 plant"...

That being said, I agree that 5 gallons isn't likely to be large enough. 10 gallons sounds about right to me.

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10 is better than 5...

but say... how quickly will a 10 gallon res warm up to room temp?

I vote for stability any day... your plants will like you for it...

I would love to know what you are basing your information on...

hmm good idea gypsy maybe i will make my own out of wood, don't i need a cover to keep light out though??

thanks for all the info guys i have a lot to think about, what about connecting 2 10 gallon totes together?

i'm thinking between 8-10 gallons will be right for me.

i agree stability is better, but i think i would rather have to chase around the ppm and ph a little bit more to have less water