RODI and fill flush how to?

[DozzerB7]

I have my RODI automated and it’s working great. Thanks Hydros for all the good work. My only complaint is that the system doesn’t flush once it get the full input from the high lvl sensor when my reservoir is full. So if I don’t manually flush it, I'll get TDS creep using up my resins unnecessarily.
How would I make it flush before turning itself off?

 

[Danny]

I have my RODI automated and it’s working great. Thanks Hydros for all the good work. My only complaint is that the system doesn’t flush once it get the full input from the high lvl sensor when my reservoir is full. So if I don’t manually flush it, I'll get TDS creep using up my resins unnecessarily.
How would I make it flush before turning itself off?

I have never had to do that on my RODI and I only change the DI resin once a year along with all the other filters. If fact I never flushed it except after replacing the filters until I got the Hydros and I have had it over 10 years. So now the only time it flushes is at the start for 1 minute and very hour it is on for 1 minute done by the Hydros. I also have a solenoid that is turned off by the Hydros at the input of the RODI unit. It does run every 4 hours for 15 minutes to refill the RO bladder if needed so It also flushes every 4 hours now.

 

[Raiden]

Not sure what and how is automated for you there. But for automatic flush a flush valve by pass with a normally closed solenoid might be a good idea. Hydros one is normally open, so can be used as well, just NC one seems like a better choice here.



If that flush valve does something magic in open position as well, then maybe would need two. Closed one of the bottom and open one up top with solenoid.

 

[Raiden]

nm hydros is NC, so all good for this

 

[DozzerB7]

I have a NC solenoid on the flush and on the feed powered by Hydros WIFI Power Bar. I was just under the assumption that it was important to flush before and after using the RODI. I’ve only been in the hobby for a couple years and just recently decided to start automating my reef. I didn’t know at what point TDS creep pollutes the resin. But I can live with replacing once a year.

 

[Raiden]

Flushing is not super effective and you would really need to do it for a while for it to be meaningful, 20-30 minutes. So I suppose that could be the driving force of the decision of when to do it, etc. Do you want to waste that much water each time you fill up 55g barrel, etc.

I used to do it for few minutes before, which probably did not do too much. I would definitely do it for a while upon carbon filter change up stream as that releases a lot of dust.

I would be interested to find out if TDS would ever really increase, as it normally should only do so with lower pressure, which technically should not happen in membrane was a flat sheet, but since it's roller up, I'm not really sure how water flows through that, if it passes through all sheets to get to the other side, I suppose clogged first sheet would lower the pressure to the second, etc. and cause bit more TDS to come through.

Some info