What quality water to put into your ATO tank?

[legrunt]

I've been wondering... what sort of water to put into an ATO reservoir?
I have mostly heard pure RODI water into the ATO to cater for evaporation, or normal salinity water to slowly increase your salinity over some time...

But what about somewhere inbetween, especially if your tank is smallish, to cater for
1) Removing water for testing (if you test a LOT)
2) skimmate

Or are the amounts too small to notice, and regular water changes should cater for it?

 

[El_Guapo13]

I've been wondering... what sort of water to put into an ATO reservoir?
I have mostly heard pure RODI water into the ATO to cater for evaporation, or normal salinity water to slowly increase your salinity over some time...

But what about somewhere inbetween, especially if your tank is smallish, to cater for
1) Removing water for testing (if you test a LOT)
2) skimmate

Or are the amounts too small to notice, and regular water changes should cater for it?

RODI would be best to top off because of the evaporation.

Water lost from testing is not much at all, so it should not be much of an issue unles your tank is like .5 gallons to maybe 2 gallons. So unless you are somehow testing so much that you are actually draining 1 or more gallons of water from your tank in a few days, you should be fine.

But for the most part, from perusing the forums, it appeara that most people who have ATOs have them specifically to combat water loss from evaporation.

 

[lapin]

Yep RODI is best

Normally salinity corrections are done at water change times.

 

[BayouReefer]

RODI

 

[X-37B]

I use rodi with 1/4 teaspoon of kalk to 5 gallons of rodi. I know its not much but it has a ph of 10 and helps keep ph in range. Mine never goes below 7.9 and gets to 8.2 during the day. Thats with running the ac in the summer and heater in the winter. Worked well on my 25 nano and works well on my 45 frag and 120 DT. It does not do anything for alk or calcium as I dose in the 45 and run a carx on my 120.

 

[AZMSGT]

No need to reinvent the wheel, RODI goes in the ATO.

When I do AUTO water changes my Water is mixed a little higher salinity than my Main tank (.1 higher, so if tank is 35, I am adding 35.1). This compensates for loss of salinity from auto testing, skimate and a couple other things I have going on. My auto water changes are 2G per day.

 

[TheKyle]

If you test that your salinity is low in the tank you can absolutely add some salt to your ato. Just make sure you are doing it in response to something you measured. I wouldn’t try seting something up that proactively accounts for this, that’s just asking for salinity problems imo as there are way too many changing variables involved.

 

[mike550]

RODI in the ATO because it’s replacing evaporated water which leaves the salt behind. I test salinity every few days and no changes from ATO.

How much water do you take for testing? I probably take 2-3 ounces. So I doubt that’s affecting salinity in any meaningful way

 

[BeejReef]

+1 to rodi in ato

if for any reason the ato overfills, I'd much rather have my salinity drop than spike.

if i was skimming very wet, for whatever reason, I just keep a gallon jug of saltwater somewhere near the tank and splash in roughly what I'm taking out.

 

[William Robinson]

Hands down RODI... However, I have added 1/2 cup salt mix before to 5 gallons of ATO water to bump up salinity but it wasnt really very effective to a 75g system.