RO plumbed to sump

[sjlesq99]

Who has their RO filter plumbed to their sump to top off? I have had it for almost two years with no problems. I am reading now that having the RO hooked up this way will shorten the life of the membrane. Anybody have any long term tests?

[MarkD40]

I have had my KENT RO/DI hooked up to my sump via a KENT float valve for 9 years. No leaks, no need to top off my tank ever. I have about 20 feet of 1/4" tubing coiled up in my sump to warm the water before it enters the RO/DI which increases the filter's output dramatically. I do flush my membrane at least once per week and I have an automatic shut off valve attached to my RO/DI so that water does not flow through the unit when the float valve is closed. I really don't feel that this should affect membrane life adversely. My present unit has been running for 2 years and I have not noticed any drop in performance or water quality. My filtered water has a TDS of around 3-5 compared to 385 for my unfiltered tap water.

I also have a "T" in my line with tubing going to a 50 gallon Rubbermaid trash can also fitted with a KENT float valve so they both get water on demand so I always have fresh water available for WC's.

[TKByrnes]

I have mine going into a 35 gallon trach can. then I have a pump in there with a tube running to my sump with a float switch to run the auto to off. I used the design on melevs site.

[steelerguy]

I have the feeling you are asking about plumbing the RO unit directly to the sump with no storage tank in between...

I think the main reason to not do this is because the filters are more efficient and last longer when they produce a lot of water at once, rather than coming on frequently producing a small amount of water to simply top off.

I don't have any long term tests to back this up, I just listened to the water filtration experts on here and the people with more experience than I. I also like the idea of having a tank with RO/DI water in it for water changes and such.

[MarkD40]

But if your RO/DI is hooked up to your sump with a float valve = NO WATER TOP OFF EVER! In my opinion, the cost of a new membrane is not so much that it outweighs the convenience of not having to ever top off your tank. At most you are shortening your membrane life by a very small amount. As I said, I flush my membrane weekly and this should counteract any ill effects that may exist with short bursts of filtering.

[gearbox-xl]

I have got my RO/DI directly plumbed into the sump for top off. The only different thing I did was to use an irrigation timer and solenoid to supply water to the RO/DI unit running 4 times a day for 5 minute intervals. I use a float valve in the sump and an auto shutoff valve on the unit itself to keep the sump from overfilling. After adjusting frequency and timing intervals this setup works flawlessly for me and reduces the stress on my RO membrane (I think). I also have the timer setup so that I can manually fill a rubbermade saltwater mixing tank to just the right level without having to keep an eye on it. Just turn it on and walk away. I do have another float valve in the mixing tank to shutoff the water supply in case of any malfunctions (Never can have too many failsafes).
My RO/DI unit is about 30 ft from my sump, in a totally different room with just a 1/4" line running to the sump.
Easily done and not that expensive. I can post some pics later when I get home if anyone wants to take a look.

[asm481]

The first few minutes an RO/DI is run you have high TDS. Called TDS creep. So this means if you turn it on for short bursts you are always dumping high TDS into your DI decreasing its life.
Also in the event of a switch, float or solenoid failure you can turn your reef into a freshwater tank.
Markd40: a TDS of 3-5 after DI means your DI is no good! Should be 0 TDS.

[mousefish]

I've did this for 5 years and it does work. I have not noticed any decline in the membrane efficiency or quality, but the membrane does need regular changes. As with what others have said, be sure to include a failsafe to stop the RO should the solenoids or float valves freeze in the open position. After 9 years of having a stable tank, I had a hermit crab get into an overflow in the refugium, cause the entire tank to overflow and flush the show tank with fresh water. Obviously not very happy with that situation and am now starting all over again - without hermits in the refugium and extra float valves to cut off the RO/DI feed.

[gearbox-xl]

The decreased DI life seems to be fairly low since I don't see much difference in the frequency of resin changes I have to do with or without the top off setup I have. I do regularly check TDS after the DI though.

[MarkD40]

ASM, I disagrree. A TDS of 3-5 is perfectly acceptable. While not as pure as distilled water it is plenty clean enough. You do not need to use laboratory grade fresh water to mix up your salt! This is an example of "reef keeper extremism" in my opinion.

[MarkD40]

Also, ASM,

1. Float valves are really reliable and are so simple and basic that there is not much that can fail. If your water line disconnects and bleeds fresh water into your tank it would take a long, long time to turn your tank into fresh water. I check my tank every day and would notice if that occurred long before irreversable damage occured. If you make sure your connections are good and tight that ain' gonna happen.

2. Life is fraught with risk. The risk of my float valve failing is way way down there as far as a risk to take. I mean it is far more likely that your house will burn down. So do you live in your back yard in a tent? My point is the the risk is very acceptable in return for the convenience of having a simple, effective way of topping off your tank.

[asm481]

I like life as simple as I can get too. I also try not to set myself up for problems. I do check on my tank every day but there is the time I go away overnight maybe a weekend. Two days could pump over 150 gallons into my 325 gallon system. Seems like brackish to me! So I will stick with my 40 gallon top off can. And floats do fail, had water in basement to prove it! No I am not setting up a tent. Just glad my tank was flushed.
As far as 3-5 TDS being acceptable, maybe to you not me. I know when I turn my RO/DI on the first few gallons are high, sometimes over 100 after RO. It comes down after a couple to my normal out of 1-2 after RO but I do not see how if I was only pumping that first couple gallons to my sump why wouldn't that be astronomical TDS. Plain and simple to me, not worth the risk.

[MarkD40]

Well ASM, we obviously have different comfort levels for risk! There is nothing wrong with playing it safe. I just feel that some small risks are worth it if it saves you some time and is convenient. I am sure your reef is fantastic because of your meticulous attention. Ah the things we go through for our little friends!

[asm481]

It is an obsession after all!

[mousefish]

The problem with top off systems, is not the day to day details. Its when you go on vacation. My reef disaster occurred one week into a two week vacation to Tokyo. I had someone checking the aquarium for me, but by the time they noticed something wasn't right, it was too late.

[sjlesq99]

Appreciate all the responses. My new setup will have my RO water plumbed to my sump. I have 2 float swiches in series working at 24 volts. the floats activate two solenoid valves in series that feed my RO water through a kalk reactor and to my sump. The water enters my sump through a mechanical float valve that is set a little higher than my other floats. This way if either of my two float switches get stuck, the water will never get any higher than my mechanical float valve. This maybe a little overkill on redundency, but I have been doing this a long time and have had some mishaps in the past.

[sjm817]

Topping off directly from the RO/DI is dangerous. My friend did this and had a big problem. The float stuck and the topoff caused quite a flood.

http://www.sump-pump-info.com/house-flood2.jpg

Good think the tank was on the main level! :D

[jtma508]

I was planning on a direct-to-sump RO/DI top-off system and had a question about design so I emailed Jim at The Filter Guys. He told me that RO/DI units are not designed to work in short bursts and that they should only run in 4gal minimum runs. He mentioned the TDS spike on start up and significantly shortened membrane life. Just thought I'd pass that info along.

[amike5]

<a href=showthread.php?s=&postid=12034683#post12034683 target=_blank>Originally posted</a> by asm481
The first few minutes an RO/DI is run you have high TDS. Called TDS creep. So this means if you turn it on for short bursts you are always dumping high TDS into your DI decreasing its life.

This has been my experience with this type of setup. I had mine set up with just a float valve for a year, but noticed that it dumps high TDS water into my tank. It would be better to add in a high and low float switch and solenoid valve on top of the float valve. This way the RO/DI has to produce a gallon or two for each topoff cycle.