Stock Tank and ATO

srobertb · Feb 9, 2023

I have a 220g (so probably 150g? Total) tank, a 50g (maybe 40g actual) refugium and a 150g stock tank sump (probably around 100g).

I keep trying to figure out how to make a return pump area to limit evaporation in the 150g. Should I care? If the entire 150g stock tank (filled to 100-ish) was the “return” portion of a traditional sump, would it cause salinity swings before the ATO kicked on? ATO is a Tunze.

Right now I’m looking at $500 for a custom acrylic tank to sit inside. A 20g H is too big to allow for a skimmer. A Rubbermaid gat age can is too.

I’m racking my brain on this. Stupid math says for every 1/4” of drop in the sump, it’s about a gallon total water loss. I don’t know how sensitive the Tunze (or any ATO) is or what a gallon of evaporation means in a 300-400g system.

workhz · Feb 9, 2023

Let's assume your math is accurate so a 1" drop, would be 4 gallons. I would hope the ATO is more sensitive than that as my super cheap one keeps it within 1/4" and almost good enough to keep the skimmer constant.

Anyway, 4 gallons in lets say 400G total volume at 1.026 would increase salinity to 1.02626

Checking on your 1/4" drop = 1 gallon seems about right (assuming a 72x18x28). As that comes out to 5.3G per inch drop. If tank dimensions are different then that changes a bit.

YOYOYOReefer · Feb 9, 2023

you display is large enough (if you hooked up a nano you could have issues) you can use the whole rubbermaid sump without baffles, i use a 150 rubbermaid with 2 300 galllon displays and cheap kamoer ato, and a backup kamoer ato

as far as evap, will depend on lots of things , tank dimmensions, overflows, lids, your home temp/ humidity etc.

srobertb · Feb 9, 2023

workhz said:
Let's assume your math is accurate so a 1" drop, would be 4 gallons. I would hope the ATO is more sensitive than that as my super cheap one keeps it within 1/4" and almost good enough to keep the skimmer constant.

Anyway, 4 gallons in lets say 400G total volume at 1.026 would increase salinity to 1.02626

Checking on your 1/4" drop = 1 gallon seems about right (assuming a 72x18x28). As that comes out to 5.3G per inch drop. If tank dimensions are different then that changes a bit.

So the stock tank is a 4x2 oval. I assume the sensor reads around 1/4-1/8 of an inch?

Not to lead you here but I think what I’m picking up is that it isn’t a big deal.

workhz · Feb 9, 2023

srobertb said:
So the stock tank is a 4x2 oval. I assume the sensor reads around 1/4-1/8 of an inch?

Not to lead you here but I think what I’m picking up is that it isn’t a big deal.

I can't imagine it being a big deal as we're talking what is likely less than a 1% (at the most) change in salinity and more likely 0.5% or less. If corals are really susceptible to that then we're all in trouble.