How to calculate ATO reservoir size?

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Aluco

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I always believe in over kill. But I do travel for work. I have a 100 gallon ATO reservoir
For a 90g? I'm assuming you have upgraded since beginning of your build thread heh.

Looks like there's already plenty of info here but I basically do 5g rodi for every 50 or so gallons. Lasts pretty much exactly 1 week in my experience
 

Kodski

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For large ATO reservoirs I feel that it's important to keep light out of them. I personally use a Rubbermaid trash can for my ATO Res. Not the large commercial trash cans, but a kitchen can with an approximate volume of 16 gallons. Got it for $15 at the hardware store. Its one with a flip top lid that I just cut a small notch in to run the wire and water line through. For my setup I have to refill it every 3-4 days. As many have said its going to vary from place to place, tank to tank. My evaporation rate more than doubled when I added a frag tank to my system. Which makes sense because I doubled my surface area.

I would suggest waiting until you get the tank up and running and simply starting with a 5 gallon pail. See how long 5 gallons lasts you and go from there. Lets say 5 gallons lasts two days. Then you know for a week you need at least a 23 gallon container. I think that is truly the only way to figure out what you'll need.
 
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My garage system ~150gallons is burning through 5 gallons every 2 days, currently. The colder, dryer weather with a skimmer running seems to evaporate my tank water quickly. My indoor tank was a couple of gallons low after forgetting to top off (by hand currently) for a day or two.

I agree that automation or a 55 gallon opaque pvc barrel to supply top off water is the ticket to vacations or just forgetting about it.
I agree.
I have a 65g reservoir for my RODI fresh water and it is low maintenance.
(Past post here if interested)

It is gravity feeds into my sump via a float valve with a powered (motorized) ball valve backup to the float valve in case float failed. (Ball valve closes when water level is too high as determined by an optical sensor. Monitored by a Neptune controller that can close the valve under various conditions as needed).

I live in Arizona and it is very dry here. Humidity is often less than 10%. During the summer months, evaporations on my 90g DT is several gallons per day.

But with the 65g reservoir, I easily have a month before I have to turn on the RODI unit to refill the freshwater reservoir.
never even really think about it.

IMO, bigger the better so long as you have proper failsafes in place and a place for the reservoir.
 

Mark Gray

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For a 90g? I'm assuming you have upgraded since beginning of your build thread heh.

Looks like there's already plenty of info here but I basically do 5g rodi for every 50 or so gallons. Lasts pretty much exactly 1 week in my experience
Originally I was running 2 tanks off it but sometimes I am gone 3 to 4 weeks at a time. I am heading to Indonesia in about a week. Won't be back for awhile
 

HankstankXXXL750

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I run mine all straight from the RODI with a Autoaqua ATO RO and it works perfectly as long as the sensors don’t give out. Periodic check allows me peace of mind and I have a high level water sensor on apex that lets me know if it is overfilling.
 

mfinn

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How do you determine how large of an ATO reservoir you'll need? Do you guesstimate? Is there science you follow? What's the best way?

I'm trying to decide how big I'll need to go for my new tank. I want it to last at least a week between refills. It's 225g... I'm considering going with either a 29g or a 40B. Thoughts?
If you are in the mind set that your maintenance schedule is every week or every 2 weeks, without fail, then it's just an experiment until you figure out how much evaporation you have over the course of that time period. Maybe add 10% -15% to that volume.
I don't like going too big. I've seen some big tanks get wiped out by a faulty float switch that flooded a tank with freshwater.
I use a 20 gallon brute container for my 240, and never leave the ro/di on after filling it.
This lasts me 2 weeks, summer or winter.
 

Mark Gray

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For a 90g? I'm assuming you have upgraded since beginning of your build thread heh.

Looks like there's already plenty of info here but I basically do 5g rodi for every 50 or so gallons. Lasts pretty much exactly 1 week in my experience
Oh no I go through about a gallon a day
 
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