Adding dosing option to existing ATO/stirrer setup

[Crashjack]

i currently have my ATO setup to where a dosing pump pushes RO to a 3-way valve where one position goes to the sump and the other goes to a kalk stirrer. I currently use this to manage alk/Ca in that I manage how long kalk and RO run every day by switching the position of the valve. I’m thinking about switching to dosing kalk but still want the ability to manage kalk/RO via my ATO (would still allow me to run kalk up to 24/7 with my ATO if I want to). I already have a second dosing pump so my thought was to: 1) add a Guest splitter between my RO reservoir and the two dosing pumps, which would allow both pumps to pull from my RO reservoir without cutting a second hole in the reservoir and adding another fitting/acrylic tube inside the reservoir; and then 2) add a second Guest splitter between the stirrer and the existing pump (keeping the 3-way valve as-is), and the second pump (the one dosing) would go into the other side of the splitter. This way, if the 3-way valve is open on the RO side, I’m dosing kalk and topping-off with RO. If the 3-way valve is open on the stirrer side, I’m running kalk via my ATO.

The possible problems I see are: 1) Both pumps pulling water through the splitter (I’ve only pushed water through Guest fittings, never pulled water through them) so I wondered if there was the potential for leaking, and 2) Since the stirrer adds some back-pressure, would there be any risk that RO could be forced back to the pump that isn’t running (since they are both dosing pumps I wouldn’t think so but wanted to make sure).

Adding the two Guest splitters sounds like the easiest way to do this but I wanted a second opinion(s). Thoughts?

 

[Brett S]

Looking at this I feel like you’re making it more complicated than it needs to be. I would just make two completely separate systems. One standard ATO and one kalk dosing system.

The ATO should just add freshwater and use a float switch to determine when it needs to top off the tank and you can just let that run all the time.

Then go ahead and dose with your kalk system. If you’re only dosing a little kalk then the ATO will make up the difference. If you’re dosing a lot of kalk then the ATO won’t run much or even run at all.

 

[Crashjack]

Looking at this I feel like you’re making it more complicated than it needs to be. I would just make two completely separate systems. One standard ATO and one kalk dosing system.

The ATO should just add freshwater and use a float switch to determine when it needs to top off the tank and you can just let that run all the time.

Then go ahead and dose with your kalk system. If you’re only dosing a little kalk then the ATO will make up the difference. If you’re dosing a lot of kalk then the ATO won’t run much or even run at all.

I might not have been clear. The tank has been running for two years with an ATO as follows: A pressure switch (Reef Angel Water Level Expansion module) controls a dosing pump that pulls RO from a reservoir and pushes to a 3-way valve where one position goes to the sump and the other goes to a kalk stirrer. Hence, when the valve is open to the stirrer, I'm topping-off with kalk. When the valve is in the other position, RO goes straight into the sump (e.g. RO bypasses the stirrer so I'm topping-off with RO). I currently use this to manage alk/Ca in that I manage how long kalk and RO run every day by switching the position of the valve. For instance, I could switch the valve to run through the stirrer at bedtime thereby topping-off with kalk that night, and then the next morning, switch the valve to bypass the stirrer, and top-off with straight RO during the next day. By managing at what time (roughly) I switch the valve each day/night, I can pretty well manage alk and Ca. I'm interested in adding a second dosing pump giving me the ability to schedule kalk dosing, while running straight RO via the ATO for top-off... BUT I want to keep my current ATO plumbing in tact so I can switch the valve to top-off with kalk any time I want.

The reason this is important is that my alk/Ca tends to start falling about a week after I replace kalk in the stirrer (I replace every 2 weeks). Right now I manage that decline by running top-off through the stirrer for longer intervals every day/night. It would be too complicated and limiting to re-program the pump dosing kalk every time I want to temporarily increase kalk addition. By leaving my current system in tact, I can increase kalk addition the same way I'm doing now by running my ATO top-off through the stirrer. I also realize that at some point, kalk alone isn't going to handle my alk/Ca needs, and I'm exploring how I want to handle long-term. Regardless of what that solution turns out to be, I will never stop adding kalk, and if my new primary method of managing alk/Ca... dosing, Ca reactor, Alk monitoring system, etc. goes down, I will still have the ability to top-off with kalk 24/7, making the temporary loss of my primary system less of an issue.