How to calculate ATO reservoir size?

[Daniel@R2R]

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?

 

[Potatohead]

For a 225 count on needing a 20-25g reservoir for a week at whatever point of time in the year the humidity in the home is at its lowest. It will last longer in higher humidity, but still I would install as big as you can reasonably fit. A 40 breeder would be great.

 

[CoralsAddiction]

No real science I’m aware of, just counting days a 5 gallon jug used to last me on 20-40 gallon tanks.
I currently run the Eshopps Pacifica 10 gallon ATO reservoir that lasts me about a week on my 120 with a sump. I also have a 15 gallon Innovative Marine reservoir I keep in the garage for trips that last over a week.
if you are okay with 29/40 looks you will be okay either way.

 

[FreshSaltH2o]

I run a 20g for my 200 and I fill it roughly once a week basically just have to do a test run and see how long (x) amount of water lasts you multiply that by however long and then you have a basic idea give or take the humidity during the day and minor fluctuations of evaporation

 

[CoralsAddiction]

One thing I’d advise is sticking with narrower and taller tanks. Wide and shallow can run your ATO pump dry quicker than tall and narrow.
for example a 20 tall is better fit than 20 long.

 

[workhz]

I do 2 tanks and aim for each one to last a week. I pump water from the second tank to the first (actual ato) to get 2 weeks out of the combo. Basically sized for my vacations. Having 2 tanks also prevents the full 10 gallons from being dumped into the sump in case of some failure. This is on a 90G.

 

[Sean Clark]

A lot of the variables go into this kind of decision. Some are personal preference and local environmental related.

I reciently calculated my topoff consumption because I realized that I had no idea how much that I actually use because it is all automated. Even the topoff of the topoff; which I feel is fairly common now.

I wanted a large topoff container simply to limit "tds creep" durring refilling because I dose directly out of the large container into the tank.

Others use smaller containers in their stands that they are comfortable refilling once a week or two.

You could set it up where it is fully automated and at that point size doesn't really matter (insert joke here)...

I have two large containers 55gal and 44gal. The 55 is my top off and the 44gal is my "just incase I need to make saltwater" reserve.

Make it easy on yourself and automate your topoff.

I have not needed to think about topoff water for years.

 

[CoralsAddiction]

Last point I’ll make here for the OP is that one reason I don’t run a big reservoir is bacteria. I noticed when I ran my 10 gallon reservoir on smaller tanks, ATO water would get cloudy when it stayed in the reservoir too long.
I like to replenish my ATO water every 3-7 days.
Good luck!

 

[KrisReef]

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.

 

[BroccoliFarmer]

My preference is make it so you don’t care. I ran a water line into my ato utilizing the Neptune solenoid and FMM kit. (Yes I could have done this as my ato but I I heard that the constant on and off would burn the RO filters). Haven’t manually refilled my ato in over a year.

 

[ScubaShane]

Last point I’ll make here for the OP is that one reason I don’t run a big reservoir is bacteria. I noticed when I ran my 10 gallon reservoir on smaller tanks, ATO water would get cloudy when it stayed in the reservoir too long.
I like to replenish my ATO water every 3-7 days.
Good luck!

Agreed! For this reason, I top off directly from my RODI with a float valve in my sump.

 

[Daniel@R2R]

Last point I’ll make here for the OP is that one reason I don’t run a big reservoir is bacteria. I noticed when I ran my 10 gallon reservoir on smaller tanks, ATO water would get cloudy when it stayed in the reservoir too long.
I like to replenish my ATO water every 3-7 days.
Good luck!

Good point! I wonder if adding a small pump to keep the water moving would fix the issue of bacteria.

As far as space constraints go, I'm planning to have the reservoirs for ATO and AWC under the stand (the stand will be 36" tall x 30" wide x 72" long) along with a frag tank. The sump and all other equipment will be in a cabinet beside the tank (for easier access and maintenance), so I'll have a pretty large area for the reservoirs if needed.

 

[PeterC99]

What’s the longest time you anticipate being away from your aquarium? (For example, let’s say 2 weeks)

Now double that time and calculate how much ATO needed. (Base on 2 week assumption, you will need one month of ATO supply). Remember, ATO needs will vary based on season, so figure peak seasonal needs.

You never know when that extended vacation opportunity or a life curveball situation will come along!

 

[fish farmer]

I eyeballed my consumption. I used to have a 10 gallon square tote that could go a month if needed, but always feared ato sticking on and turning my tank to freshwater.

I upgraded to a different ato with a smaller pump and a tall 3 gallon food container. I use about 2 gallons of water per week.

 

[Mical]

To OP - there's a few variables that come into play. Mainly time of year and/or if you have glass lids or screens on top.

I have a 120 & 65 and both have glass lids and both evap 3 gals per week. If I switch to screens it jumps to almost 6 gals per week. These #s are year round here in Minnesota. Both have 10gal reservoirs so if I'm out of town for over a week it's not a concern.

 

[vabben]

On my 120, I have a 5-gallon ATO container. But have it programmed through my Apex to automatically refill. Best decision I have ever made. I have two fail-safes on it just in case it starts to overfill.

I have a PMUP in my 100-gallon RODI barrel in the basement. PMUP has no issues pumping water from the basement to my tank.

 

[threebuoys]

The 29 will probably work. Put some type of cover over the reservoir to reduce evaporation there. Likewise, cover as much of the surface area of the sump to reduce evaporation there too.

 

[Thomas Jedlicka]

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?

I have a large system too and out of convenience I ran a float valve on my sump. I never have to refill a reservoir so if possible I would suggest doing it! but if not I think 40 breeder would work. i would just be mindful of how fast it drains, it can vary depending on season and other factors

 

[nereefpat]

So, the easy math tells me that a 29 gallon would last more than 7 days at 4 gallons per day. That may be enough, but that is a biggish tank, and I assume Fontana is hot and dry.

If the stand is truly 30" wide, then you could put in a 29 gallon sideways, and then have room for another if needed.

 

[vetteguy53081]

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?

Bigger is better. I use an 18 gal ATO which is black acrylic and I go quite a while before need to refill