View Full Version : Auto Top Off Help

07/07/2017, 12:22 PM
Hi All,

I've been in the hobby for a while but I've never had an auto top off. I'm familiar with how it works but need some additional help. I am currently in the process of getting all the equipment for my latest set up and need some feedback.

Below is a picture of the tank. Of course I'll have a refugium on the bottom. If you take a look on the right side of the tank you'l see a bunch of wires. There is an RODI system set up in the garage and the water tubing runs through the house into those tubes you see on the right. So I have the RODI which makes water, now the question is how do I get that RODI to stay on and dump in water only when the tank is low? I can't seem to wrap my head around everything. Any help would be much appreciated! The goal is to constantly have the tank fill up itself without have to manually adding water every day. Thank you!

http://i23.photobucket.com/albums/b363/Playerz57/51968802659__1850B040-FB31-44A8-BA01-152B167ED921_zpsyvpsp9re.jpg (http://s23.photobucket.com/user/Playerz57/media/51968802659__1850B040-FB31-44A8-BA01-152B167ED921_zpsyvpsp9re.jpg.html)

07/07/2017, 12:58 PM
I would suggest against using a RODI unit as an ATO. With a source for unlimited water things could go very badly. Now if you wanted to fill a separate container for your ato I could see that being alright. Still chance of a flood but it's not going to hurt the tank.

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07/07/2017, 01:22 PM
Taking water directly from the output of the RODI is not a good idea for at least 2 reasons..
#1-As stated above a failure means an unlimited supply of water could flood your house,etc...
#2-When an RO/DI system is first turned on the TDS of the output water is higher and then after a little bit it drops back.. Well short cycling like that means you are always adding "higher than zero" TDS water to the tank.. That might not be an issue or that higher TDS could cause problems..

In general the preferred way to run an ATO system is by having a separate container (ATO container) that holds gallons of water. Size of that container depends on how often you want to fill it and a little calculation to see that "IF" the whole thing drains into the tank will it cause a flood or a severe lower salinity problem..

Now you've got a container that you fill weekly or monthly or automate to fill up once a week or many other options..
So then you need to pump water from that container into the tank..
This would typically be via a pump operated by float/optical/pressure sensors.. Those sensors see the level of water drop (in the section of your sump that the return pump is located only) and they tell the pump to turn on/off..

Now surely with a tank that size you are going to run a controller of some sort right? if so look into what options it has for ATO..
Or let us know what controller you will run and we can add more information for you...

07/07/2017, 01:25 PM
Use a float valve and ideally a float switch or something along with a solenoid. I'm
A bit weary of connecting the RODI to the tank as it can be big if it fails and stays on for days

Plus you wear out your membranes quicker. The apex ATK has a solenoid you can use over the pump. It's one option that has some redundancy built on

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07/07/2017, 01:30 PM
Got it thank you. So essentially I'll have to get a storage container to sit in there which will be filled up. Now, is the water supply manually turned on from the garage to fill it up then when it's filled I manually turn it off? Then of course have the auto top off to carry the RO water from the reservoir to the fuge.


07/07/2017, 01:48 PM
Got it thank you. So essentially I'll have to get a storage container to sit in there which will be filled up. Now, is the water supply manually turned on from the garage to fill it up then when it's filled I manually turn it off? Then of course have the auto top off to carry the RO water from the reservoir to the fuge.


yes.. manual is best.. as again a failure of the supply to the ato container could also stick on and flood that ..then your floor..

and don't forget.. redundancy..redundancy..redundancy..
Multiple float switches,etc.. are better than a single one..

But again.. see what your reef controller system uses and investigate that well..

07/07/2017, 01:51 PM
Sounds good! Thank you!

So I guess the plan is to find a large enough water tank to keep next to the tank, manually turn on the RODI until the tank is filled up, turn it off, then find an ATO system preferably with multiple safety features to cut off the water supply in case one of the senors goes bad. Makes sense.

Thanks again!

07/07/2017, 01:56 PM
yep.. enjoy..

07/07/2017, 03:30 PM
Here's a cheap solution but it works. I use a smart ato micro for an ato. https://uploads.tapatalk-cdn.com/20170707/2401257bf6b902f8fce4b2c89dee0cf2.jpg

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07/08/2017, 08:00 AM
I use water direct from my RO unit, but I put the ATO on a timer, so if there is any problem, the time it can run is limited. The RO water goes into my sumps, which have an emergency drain. If salinity drops to a specified point, the return pump shuts off anyway, so that it will not continue to lower salinity in the display. Doing this has eliminated ALL involvement on my part, for doing top off.

Whatever setup you use, I'd recommend putting a timer on the ATO.

Now...back to your original post. It seems you're trying to gain knowledge on how the ATO works and needs to be set up. You really are best to have a sump, or you will have to put a float sensor IN your display tank. The reason is that water evaporation (water level drop) is evident in the tank when you don't have a sump. When you have a sump, it's in the part of the sump that the return pump sits in.

Most people choose to have a container of stored RO water, and will use a float switch to feed it in when the float switch signals low level. They will feed it in through gravity, or using a pump that's switched off and on. I would suggest a float VALVE also, as it can mechanically shut off water flow, even if any electronic stuff fails.

Keep in mind that while many people frown on using water straight from the RO unit, and tell you about redundancy... there is risk with any method, and possible ways to create redundancy. You don't necessarily have to go with any specific number or types of redundancy measures. As I mentioned, I run straight from RO, but have more redundancy than most people that don't.

07/08/2017, 11:26 AM
Running straight from an RO/DI unit isn't just about redundancy, you'll also go through DI resin much quicker - maybe two or three times as fast - as compared to making water in larger batches. And if you're not using DI, then you're basically topping off with dirty water all the time.

Turn your unit on and collect the first gallon that comes out of the membrane (before the DI) and measure TDS. Then let it run for at least 5 gallons, collect the 6th gallon, and check it again. There will be a pretty significant difference.

07/08/2017, 11:51 AM
I agree with the others about running the RO/DI SYSTEM IN SMALL BURST. bad idea you will get only higher tds.

My ato is a 15 gallon tank that sits next to but above my Sump . There is a 1/4 inch bulkhead in the side of the tank 4 inches up.Its connected with 1/4 inch hose to a float valve in my sump. I fill the 15 gallon tank once a week and clean it out once every 6 months as i also add kalk to this tank when i clean it out. Each week when i top off the tank i do so by turning a valve connected to my Mixing / water change pump with the RODI TANK Valve open.. This stirs up the kalk .

I have never had the float valve to fail NO computers or sensors or power needed. I do clean the float valve once a month at the same time i clean my skimmer collection cup and its waste container that has a house sump pump float switch in it in case the skimmer over flows, it will shut off the skimmer. I put about 1/4 cup of bleach into this container to keep it from smelling.

The reason i have the 15 gallon tank instead of plumbing to my sump directly from the rodi storage tank is that if the float valve did fail and 15 gallons of kalk laced ro water get dumped into my tank at the rate the 1/4 inch line could do would not crash the water volume i have . This is the most important thing about any ATO. Rather controlled by a Controller float valve sense or switch Never HAVE A ATO Tank that can crash your tank .....

Welcome Back and good Luck