Size of reservoir without the need to top-off for 2 weeks?

In the very interesting topic of KLX (https://www.rollitup.org/t/the-klx-way.960314/) we discussed the size of a reservoir. He is doing an E&F grow.

I am really curious about experiences that members here have.

What size do you think your reservoir should be if you want...
A) No need for topping off at all for 2 weeks?
B) Not risking that you'll have really disproportionate nutrients i.e. way too many of one element and not enough of another?
C) A total dumping of everything after 2 weeks and filling the reservoir up again with fresh tapwater and nutrients,

For discussions sake let's state that you have a tray or a growing area of 4 x 4.
Of course experiences from people who have growrooms, trays, whatever, with other sizes are more then welcome.
Also let's say the 4 x 4 is full of budding plants.

So I wonder what size would be needed to do no work for 2 weeks and not jeopardizing your plants/roots, and have a great yield in the end.

It completely depends on table size, plant size, and plant count .
But 4X4 full of budding girls, I'd say a 50g would do it.

Thanks, I added 'budding plants' in the first message.

Airwalker16 said:

It completely depends on table size, plant size, and plant count .
But 4X4 full of budding girls, I'd say a 50g would do it.

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i second this, currently my main flowering room is 4x2 with 6 girls in it and i go through 28g of nutes about every 12 days, mine is a drip to waste system though. fairly confident 50g would get your through 2 weeks with E&F, id go with a 55g just to be safe though, plus 55g drums are very common, ive got like 6 in the garage actually..

DailyBlastin said:

i second this, currently my main flowering room is 4x2 with 6 girls in it and i go through 28g of nutes about every 12 days, mine is a drip to waste system though.

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Great, so you leave your reservoir for 12 days totally untouched?

Keesje said:

Great, so you leave your reservoir for 12 days totally untouched?

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yupp, i do a good clean out of it about once a month but once its filled i dont fuck with it until it needs filled again.

DailyBlastin said:

yupp, i do a good clean out of it about once a month but once its filled i dont fuck with it until it needs filled again.

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And I do you have a decent yield?
(I ask because some people say, that it is impossible to get a good yield if you do not change, adjust and top off your reservoir constantly)

Keesje said:

And I do you have a decent yield?
(I ask because some people say, that it is impossible to get a good yield if you do not change, adjust and top off your reservoir constantly)

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i would rethink e&f for a 2 week reservoir change. your nute profile will be way out of whack for that long.

i do dtw waterfarms and my res lasts 2 weeks (about 25 to 30 gallons)

rkymtnman said:

i would rethink e&f for a 2 week reservoir change. your nute profile will be way out of whack for that long.

i do dtw waterfarms and my res lasts 2 weeks (about 25 to 30 gallons)

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Good point, DTW or RDWC with a top-off res would be the way to go.

DTW would be easier than fine tuning the top-off.

There is a point where the size of the reservoir is so big, that the nute profile will not be 'out of whack'.
Or at least not in such a way that it harms the growing in any way.

I am looking for experiences of people who have a (large) reservoir and do not adjust, not top off or anything else.

Keesje said:

There is a point where the size of the reservoir is so big, that the nute profile will not be 'out of whack'.
Or at least not in such a way that it harms the growing in any way.

I am looking for experiences of people who have a (large) reservoir and do not adjust, not top off or anything else.

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i gave you my experiences, do with it what you want. you can find the 300 gal IBC totes on craigslist cheap. that should last a bit

I thank you for sharing your experience.
And also thanks for the info that you have your nutrients in your reservoir for 2 weeks.
I know it is for drain to waste, but still.

Keesje said:

I thank you for sharing your experience.
And also thanks for the info that you have your nutrients in your reservoir for 2 weeks.
I know it is for drain to waste, but still.

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not really. with the waterfarms (rdwc technically), i feed once a day for enough time to get maybe a minute of runoff. so in a 2 gal res, it probably gets a fresh 1 gal batch of nutes each day.

if you really wanted to know for your situation, have your nute profile tested on day 1 and day 14 and see how different they are. and then you have to find the sweet spot where you have enough for 2 weeks and aren't throwing away a bunch of nutes too.

That would be a possability.
Good idea.
In the past I knew a company that analised your water. Let's see if they are still around.

200L should do it, but as others have said a 55 gallon drum would be perfect. You would just need to do some trial and error with your starting ppm so that at the end of the 2 weeks the ppm's are roughly the same as when you first filled the tanks.

Of course the ratios of NPK are not going to be exactly the same on day 14 as day 1 but if your goal is reducing work versus effectiveness it will work out fine!

klx said:

200L should do it, but as others have said a 55 gallon drum would be perfect. You would just need to do some trial and error with your starting ppm so that at the end of the 2 weeks the ppm's are roughly the same as when you first filled the tanks.

Of course the ratios of NPK are not going to be exactly the same on day 14 as day 1 but if your goal is reducing work versus effectiveness it will work out fine!

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This! As other stated of course your nute profile will not be the same after two weeks as it was day 1, but to expect it to be would be rediculous, hell if i could get a nute profile to stay the same that long i just wouldnt ever change it lol. but no you should be fine, i ran E&F buckets for a while before i switched to drip to waste, i would usually only let a nute batch go for a week before draining and refilling but im fairly certain you can stretch it to two weeks, im a bit OCD when it comes to keeping things clean so my once a week drain and refill was mostly due to that rather than the change in nute profile. as long as you still have a decent ppm and ph you can let that batch go until the plants use it all up, sadly in my case, they never use it all up before the urge to clean that res kicks in

For a 4x4, a 55g drum and a Dosatron. I'd say a 30g would work but in a high transpiration state you'd lose too much liquid volume over a 2 week period. 55g gives you the added comfort.

Its unfortunate that a float valve is unusable on a flood and drain.

klx said:

200L should do it, but as others have said a 55 gallon drum would be perfect. You would just need to do some trial and error with your starting ppm so that at the end of the 2 weeks the ppm's are roughly the same as when you first filled the tanks.

Of course the ratios of NPK are not going to be exactly the same on day 14 as day 1 but if your goal is reducing work versus effectiveness it will work out fine!

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A 55gal "drum" is outta the picture unless your table is higher than it lol.

You need a TOTE like HDX brand from Home Depot that's LOW and WIDE to fit under the tray.

Airwalker16 said:

A 55gal "drum" is outta the picture unless your table is higher than it lol.

You need a TOTE like HDX brand from Home Depot that's LOW and WIDE to fit under the tray.

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I noticed they now have 40 gallon ones now available with black lids no less

Gota love lowes and hemp depot