RO/DI Fittings Question

[cbau45]

I'm doing a tune up on my RO/DI unit. I have a Coralife 50gpd 4-stage unit. I am in the process of adding a pressure gauge, a flush kit, & a dual in-line TDS meter. I'd like to replace the compression fittings with the John Guest speed fittings. Does anybody know what the standard size fittings are for the intake tube and the return lines?

[AZDesertRat]

1/4" MIP x 1/4" tube size is the most common.

If I might make a couple suggestions. Forget the flush kit, they have no proven documented value other than to lighten your wallet and give you a warm fuzzy feeling. They don't do anything. You would be much better off installing a simple tee and ball valve between the RO membrane and the DI filter as a DI bypass. When you first start making water open this valve and let the first quart or so go down the drain to flush the TDS creep out before it hits your DI and shortens its life. This is proven and has value. Flush kits do nothing for TDS Creep since all they do is pass water around the waste side of the membrane, not the treated side and the volume and velocity is not nearly enough to scour the membrane.

Next, rather than an inline TDS meter you are much better off with a good handheld that costs the same $25 or less. the inline is limited to two TDS readings, usually RO only and final or RO/DI TDS. But, to troubleshoot a RO/DI you need three TDS readings, tap water, RO only and RO/DI so you arestuck with insufficient information. Plus the inlines are not truly temperature compensated and monitor air temperature not wate rtemperature so can be significantly off unless your wate rand air are exactly the same which is rare.

A good handheld is much more versatile, can be used on tap water, RO, RO/DI, bottled distilled, the LFS water, your buddies water, drinking water etc and is temperature compensated so is much more accurate. Good ones like the HM Digital TDS-3, TDS-4TM and their new AP series all have a built in digital thermometer too so serve dual purpose and all are around $25 or less.

My third suggestion is to measure your actual waste ratio using a measuring cup and watch or clock to ensure it is close to 4:1. Most vendors use a fixed flow restrictor and its really not a one size fits all and could be as high as 20:1 wasting water and reducing the RO efficieny or as low as 2:1 fouling the RO membrane and shortening its life driving the cost of ownership up. If it is not close to 4:1 I suggest buying a $5-$6 capillary tube flow restrictor and trimming it to fit your own unique water conditions.

[cbau45]

1/4" MIP x 1/4" tube size is the most common.

If I might make a couple suggestions. Forget the flush kit, they have no proven documented value other than to lighten your wallet and give you a warm fuzzy feeling. They don't do anything. You would be much better off installing a simple tee and ball valve between the RO membrane and the DI filter as a DI bypass. When you first start making water open this valve and let the first quart or so go down the drain to flush the TDS creep out before it hits your DI and shortens its life. This is proven and has value. Flush kits do nothing for TDS Creep since all they do is pass water around the waste side of the membrane, not the treated side and the volume and velocity is not nearly enough to scour the membrane.

Next, rather than an inline TDS meter you are much better off with a good handheld that costs the same $25 or less. the inline is limited to two TDS readings, usually RO only and final or RO/DI TDS. But, to troubleshoot a RO/DI you need three TDS readings, tap water, RO only and RO/DI so you arestuck with insufficient information. Plus the inlines are not truly temperature compensated and monitor air temperature not wate rtemperature so can be significantly off unless your wate rand air are exactly the same which is rare.

A good handheld is much more versatile, can be used on tap water, RO, RO/DI, bottled distilled, the LFS water, your buddies water, drinking water etc and is temperature compensated so is much more accurate. Good ones like the HM Digital TDS-3, TDS-4TM and their new AP series all have a built in digital thermometer too so serve dual purpose and all are around $25 or less.

My third suggestion is to measure your actual waste ratio using a measuring cup and watch or clock to ensure it is close to 4:1. Most vendors use a fixed flow restrictor and its really not a one size fits all and could be as high as 20:1 wasting water and reducing the RO efficieny or as low as 2:1 fouling the RO membrane and shortening its life driving the cost of ownership up. If it is not close to 4:1 I suggest buying a $5-$6 capillary tube flow restrictor and trimming it to fit your own unique water conditions.

Thank you kindly for the feedback, I really appreciate it. I'm not so concerned about the flush kit really scrubbing the membrane as I am just using it to push the old water out of the system and if it takes some of the build up off of the membrane too, then that's cool with me.

As for the TDS meter I have the dual in-line one, a single in-line, & a handheld. A little redundant, yes, but I like to measure for accuracy.

I have considered changing out the flow restricter to a capillary tube restrictor, however, I will try your test first to see what my waste / good water ratio is (thank you for the suggestion). These are relatively cheap upgrades to the unit so i'm not too concerned there. I just want to make sure things are consistant from the source.

[AZDesertRat]

Stick a tee and ball valve between the RO and DI for two reasons. One is as I already mentioned to use as a DI bypass on start up to flush the TDS creep out but the other is to be able to draw a sample of RO water in a glass to compare your handheld meter to your inline meter. I think you will find the handheld is superior and soon quit using your inlines as I have. I have two dual inlines and rarely ever turn them on anymore, only as a litmus paper type test, prescence/absence but no level of accuracy.

When you start the RO you do push the old water out using the 4:1 waste ratio, the flush kits don't do much more than that if anything. To properly use a flush kit, if there is such a thing as proper, you need to run it for sevceral minutes each and every time you make water, before shutting it off, not when you start it. Once it is sitting the TDS osmoses to the treated side (TDS creep) so the bad stuff is now on the other side of the membrane where a flush kit does no good since its on the waste side.

[cbau45]

Once I get all of my replacement filter cartridges and fittings i'll have to run some tests. I'll document my findings on this thread for others to review as well.

Thank you again, for the information. This is invaluable as this piece of the filtration is one of the most important IMO.

[cbau45]

Stick a tee and ball valve between the RO and DI for two reasons. One is as I already mentioned to use as a DI bypass on start up to flush the TDS creep out but the other is to be able to draw a sample of RO water in a glass to compare your handheld meter to your inline meter. I think you will find the handheld is superior and soon quit using your inlines as I have. I have two dual inlines and rarely ever turn them on anymore, only as a litmus paper type test, prescence/absence but no level of accuracy.

When you start the RO you do push the old water out using the 4:1 waste ratio, the flush kits don't do much more than that if anything. To properly use a flush kit, if there is such a thing as proper, you need to run it for sevceral minutes each and every time you make water, before shutting it off, not when you start it. Once it is sitting the TDS osmoses to the treated side (TDS creep) so the bad stuff is now on the other side of the membrane where a flush kit does no good since its on the waste side.

AZ, upon inspection of my RO unit I noticed there are flow restrictors on both lines coming out of the RO unit (good & waste water) is this normal? I thought the restrictor was typically on the waste line only.

[AZDesertRat]

There should not be a flow restrictor on the treated water line, only the waste line.
Are you sure it isn't an inline check valve on the treated line?

Photos of the plumbing would help.

[cbau45]

Here's a few pics of the unit. It's a pretty basic unit which is why I want to make the upgrades. I'd like to change the fittings from the JACOs to either the John Guest speed fittings or the Mur-lok fittings.
http://i246.photobucket.com/albums/gg108/cbau45/null_zps8a7124df.jpg (http://s246.photobucket.com/user/cbau45/media/null_zps8a7124df.jpg.html)

http://i246.photobucket.com/albums/gg108/cbau45/null_zpsa630ca3a.jpg (http://s246.photobucket.com/user/cbau45/media/null_zpsa630ca3a.jpg.html)

Here's the restrictors I was talking about. it looks like there is one in each line.
http://i246.photobucket.com/albums/gg108/cbau45/null_zps6ae34d86.jpg (http://s246.photobucket.com/user/cbau45/media/null_zps6ae34d86.jpg.html)

Items I want to add (I have two of the inline TDS meters, only 1 pictured)
http://i246.photobucket.com/albums/gg108/cbau45/null_zpsc83f908b.jpg (http://s246.photobucket.com/user/cbau45/media/null_zpsc83f908b.jpg.html)

[AZDesertRat]

You should only have a flow restrictor in the waste line, never in the treated line. Not sure what someone was thinking there? You might pull those out and check to be sure thay are not just an insert to help the plastic tubing seal and not restrictors.

If you decide to install the flush kit, which I would not personally, it has a flow restrictior built into it so remove both original restrictors in that case. The flush kit will have a restrictor in the line you show cut in tow pieces and the ball valve in the other line bypasses it when open and flow through the restrictor when closed. I wouldn't wste my time and money though and just install a correctly trimmed restrictor in the waste line to achieve a 4:1 waste ratio which is wha tactually does flush a RO membrane when in use.

Since you have two dual inline TDS meters you can install the IN probe of the first one in the incoming tap water line and the OUT probe after the sediment and carbon block filters but this doesn't tell you much since they remove TSS or suspended soldis and not TDS or dissolved solids so those readings will be withing 1 or 2 TDS of each other. The second meter can have the IN probe between the RO membrane and DI to monitor the RO TDS and the OUT probe on the final RO/DI TDS.

I have two dual inlines but honestly would sell them cheap since I neve rturn them on. My COM-100 handheld is much much more accurate and more versatile since it can read anywhere, not just a dedicated point and it is temperature compensated unlike the inlines and has a built in digital thermometer too. I look at the inlines as a litmus paper test, presence./absence, or ballpark close.

The inline pressure gauge will go between the carbon block and the RO membrane to monitor plugged filters or headloss.

[cbau45]

You should only have a flow restrictor in the waste line, never in the treated line. Not sure what someone was thinking there? You might pull those out and check to be sure thay are not just an insert to help the plastic tubing seal and not restrictors.

If you decide to install the flush kit, which I would not personally, it has a flow restrictior built into it so remove both original restrictors in that case. The flush kit will have a restrictor in the line you show cut in tow pieces and the ball valve in the other line bypasses it when open and flow through the restrictor when closed. I wouldn't wste my time and money though and just install a correctly trimmed restrictor in the waste line to achieve a 4:1 waste ratio which is wha tactually does flush a RO membrane when in use.

Since you have two dual inline TDS meters you can install the IN probe of the first one in the incoming tap water line and the OUT probe after the sediment and carbon block filters but this doesn't tell you much since they remove TSS or suspended soldis and not TDS or dissolved solids so those readings will be withing 1 or 2 TDS of each other. The second meter can have the IN probe between the RO membrane and DI to monitor the RO TDS and the OUT probe on the final RO/DI TDS.

I have two dual inlines but honestly would sell them cheap since I neve rturn them on. My COM-100 handheld is much much more accurate and more versatile since it can read anywhere, not just a dedicated point and it is temperature compensated unlike the inlines and has a built in digital thermometer too. I look at the inlines as a litmus paper test, presence./absence, or ballpark close.

The inline pressure gauge will go between the carbon block and the RO membrane to monitor plugged filters or headloss.

Thanks again for the info! If those pieces in the waste line and treated line were not flow restrictors then this unit does not have a restrictor on it at all and that doesn't make much sense either. I got all of this stuff at no cost so i'm not too upset if some of it does not get used. If the first TDS meter would only be reading the TSS from the sediment and carbon blocks then there isn't much advantage in me installing it. I'll toss the other one in between the RO membrane and DI as you suggested but i'll use the readings as more of a ballpark suggestion on when my filters start to go. I'll have to pick up a new handheld TDS meter and run a few tests. I think i'll put a better restrictor in the waste line and remove the two that are in the unit currently. that will likely help with my overall water production as well I would think.

Presently this unit is rated for 50gpd, do you see any advantages / disadvantages to me replacing the RO membrane & flow restrictor to 75gpd?

[AZDesertRat]

The 75 or Spectrapures 90 GPD will produce treated water faster so less waiting around.
If your system is automated and goes in to an ATO storage container and turns on and off by itself its no big deal but if you are using a faucet adapter and making water manually then the larger membrane might be a blessing as it frees up your faucet faster. It takes hours to make much usable water and I know my wife would be upset if I had the kitchen faucet occupied for 8-10 hours straight making reef water. I ended up installing my system over the laundry sink in the garage and using a brass wye off the washing machine cold water supply so nothing is affected when its in use.

The Dow Filmtec 25, 50 and 75 all are 96-98% rejection rate, the Dow 100 GPD iso nly 90% rejection so not suited for our purposes since it eats DI resin like crazy. Spectrapure takes that same 75 GPD and treats it with a special proprietary process to improve that rejection rate to better than 98% so DI lasts longer and the GPD goes up slightly too. For every 2% you increase the rejection rate you double the life of your DI resin so a new membrane can pay for itself quickly if yours is less than 96-98% efficient.