RO and AWC (using DOS) sharing the same 1/4 drain line

[BrettDS]

I permanently installed my RO filter in the stand of my tank and made two 35 foot runs of 1/4 inch tubing to the nearest bathroom (pretty much entirely horizontal.. maybe a couple of inches of head, if that)... one for the supply and one for the drain.

I just got a Neptune Apex DOS which I'm using for auto water change and I got a T connector and ran it into the same 1/4 tube that the RO filter uses to drain so the DOS can send the water it removes from the tank right down the drain.

However, as I'm looking at this I'm wondering if it would be wise to use check valves on both drains before the T. I'm not sure there's too much of a risk of either system backing up into the other as I don't believe that either are terribly high pressure, but what do you think? Good the way it is or get check valves?

 

[skeeter_ca]

I would add check valves just to make sure a back flow problem doesn't happen. Also you mentioned you mounted the RO filter under the tank. Are you running the supply line straight to your sump or to a reservoir to then be used for topoff water?

skeeter

 

[BrettDS]

Also you mentioned you mounted the RO filter under the tank. Are you running the supply line straight to your sump or to a reservoir to then be used for topoff water?

Unfortunately I have no room for a separate reservoir for RO water for ATO, so it's plumbed directly to the sump, however, I have a number of safeguards in place to prevent it from flooding or overfilling.

First, there is a NC electronic solenoid valve controlled by my apex on the feed line to the RO filter. This is only turned on when something is calling for RO water. The output of the RO filter is split with a T, one part going to my NSW reservoir to refill it and the other going to the sump for ATO. There are two more NC solenoids (one on each of these lines), also controlled by the apex. The sump line terminates in a float valve in the sump.

The Apex only allows the sump side of the RO filter to run for 2 minutes every hour. Two minutes an hour is little more than what is required to keep up with evaporation, so if the float valve did fail the level in the sump would rise, but it would take many hours before it was dangerously high.

Additionally there are two float switches above the water line in the sump and if either of those are triggered the apex will shut off both the RO supply solenoid as well as the solenoid that shuts off the whole RO filter. These will also email me and sound an audible alarm.

Finally, even if the float valve, both solenoids, and both float switches fail, there is a leak detector on the floor of the stand that will detect any water that overflows from the sump and will shut the whole system down, but hopefully it won't ever get to that point