BCrocker said:

I am in the process of setting up my first UC run. *applause*

The set will be 28 site 13 gallon, 28" centers. I am planning on a shorter veg, (4 weeks) then flip, as the plants will be closer together.

I have done research and searched forums although I am not sure yet on how I am to place my res , top off res , chiller etc.

I have a 955L (252US Gal) res. that will be getting fed RO water on demand via float valve.

I am not sure how to setup/plumb the top off. res... Should I use the 955L as a holding for RO water, get a 100 gallon for the top off?

The system max I believe would be 28 x 13 gallons + epicenter + volume in pipes = about 400 gallons?
To my understanding I will want to run each site at about 9.75 gallons. So the entire system would be about 275 gallons.


I have a 1000L holding tank of RO water, but not sure if I use that as the top off, or I plumb it to another smaller res, via float valve.

I could use a 50 gallon barrel as a top off res and just fill that with RO water when it requires. Although, I am not sure how I would balance the nutrients back to where they should be.

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You are going to want something around 300g Res.

I have a 6k room that is 15 site evo 13g setup. In that room they drink 40g a day.

You would be mixing nutes almost everyday with a 100g top off.

What I did with my RO holding tank was to T off the bottom one to a hose, and use gravity feed where you need RO, and for the top off tank, I plumbed PVC into it from a inline pump off the other side of the T on the RO tank so I could flip a switch and pump RO into my topoff tank, and I fill to whatever amount I wish to make up. Usually make 5 days worth or so.

Zensai said:

You are going to want something around 300g Res.

I have a 6k room that is 15 site evo 13g setup. In that room they drink 40g a day.

You would be mixing nutes almost everyday with a 100g top off.

What I did with my RO holding tank was to T off the bottom one to a hose, and use gravity feed where you need RO, and for the top off tank, I plumbed PVC into it from a inline pump off the other side of the T on the RO tank so I could flip a switch and pump RO into my topoff tank, and I fill to whatever amount I wish to make up. Usually make 5 days worth or so.

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So I need to get another res that is about 300 gals, and use the 252gal as my storage.

Put a T on the bottom of the 252 gal storage tank, connceting it to the Top Off Res and one to something else if needed

Then connect top off res to the Epi Center, with shut off and float valve. This will let the system automatically top off , correct? Or do you have the top off shut off and do it manually?

I suppose when in full bloom these might be using 100gal a day. Oh dear, this is a lot of water lol

I top off with cal/mag'ed RO from a 55gal drum through the epi float, that i fill and dose on feed day and maintain as needed. I keep separate barrels for fresh RO storage, dual 55's.

My 10k 9plant 8gal system can take down 20gal a night.

A float valve on both reservoirs would create a self perpetuation top off of R.O. water form the holding tank.

float your R.O.
float your smaller holding tank.
float your epicenter.

Plants drink, epicenter gets water from smaller...lol 200-300gallons doesn't seem "small" tank, then the float in the smaller tank would bring water from the main 1000gallon holding tank and the float there would turn on your R.O. fillin g the system nicely.

Powdery said:

A float valve on both reservoirs would create a self perpetuation top off of R.O. water form the holding tank.

float your R.O.
float your smaller holding tank.
float your epicenter.

Plants drink, epicenter gets water from smaller...lol 200-300gallons doesn't seem "small" tank, then the float in the smaller tank would bring water from the main 1000gallon holding tank and the float there would turn on your R.O. fillin g the system nicely.

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^^ This is what I am going to do , as well as a shut off valve between the holding and top off res. My holding res is only 252 gallons (1000L), and I haven't gotten the top off res yet, although I have been looking at a 270gallon vertical tank.

Oh yes, I might be only running 24 sites instead of 28, so less volume of water.

I suppose I will have to have the top off res *not* get topped off automatically, as it would dilute the nutrient solution. When it gets low I would fill it up and re-mix nutrients

BCrocker said:

^^ This is what I am going to do , as well as a shut off valve between the holding and top off res. My holding res is only 252 gallons (1000L), and I haven't gotten the top off res yet, although I have been looking at a 270gallon vertical tank.

Oh yes, I might be only running 24 sites instead of 28, so less volume of water.

I suppose I will have to have the top off res *not* get topped off automatically, as it would dilute the nutrient solution. When it gets low I would fill it up and re-mix nutrients

Click to expand...

The issue with that is you are topping off with concentrated nutes, then you are dilluting your top off over time. I don't think that is really what you want to do.

Here is exactly how I have my rooms setup. I have 1 tank that is RO water only, that is fed from the RO system with a float valve. On that tank I have a T, one end goes to a on/off valve that I can drain the tank if I ever need to. the other end of the T goes to a inline pump. My top off tank, each week or twice a week. I fill with a set amount of RO from the RO tank using the pump and the hose/pvc that is piped on the output of the pump. Once I have filled the top off tank. I mix my nutes in full in that rez. On the bottom of the top off tank I have the same type of setup. I have T, one with a on/off to drain out the tank if I want to clean, or change it early. then the other going to a on/off with 3/8" poly line that goes the the float valve in the UC. This way as the plants drink the system is slowly being topped off with full strength solution. I control the level in the UC by the float valve (duh). :)

Now if your nutes are too strong and the PPM/EC meter you are using in the Epi is showing signs that they are drinking more water then nutes, then you simply just pump 10% more pure RO into your Top Off, dilluting it down.

You do not want to directly connect your RO/Top Off tank because you do not want to have it Auto dillute your topoff, and you do not want to cross contaminate the RO storage tank. Based on your size of your one container, I would buy a 300g for RO storage, and use the 255 for the Top Off, that way you can always fill the full amount in your Top Off from your RO supply.

Awesome. Perfect information here. Thanks! :cool0041:

One more thing, ph. Do you have a meter in the top off and a meter in the Epi? Do you only ph down the top off res? I was thinking of adding a ph auto doser to the top off res.

I have a meter in both, when I mix the nutes I set my ph to 5.6 and let it swing in the UC until I refill my topoff. It usually will swing between 5.8 and 6.3 in the UC depending on how hungry they get