RO flow rates

[FlowerFarmer]

Sup friends,

Been having some troubles with my RO output.

I'm running a Merlin on a nasty 400-600ppm well or so. Lots of sediment.. I see lots of orange funk on my house pre-filter..right out of the well.

I tried running a Tall Blue pre-filter in front of my Merlin to save the life of my membranes, but got a lot of water hammering and poor PSI (even with use of a booster) regardless of how I set it up.

So.. I took out the Tall Blue and just had it going through my home pre-filter (sediment) and then to merlin booster pump.. and then through Merlin. All new filters a few weeks back and things were flowing good once again. I was pegging 60psi on the Merlin and getting quick barrels filled.. around .45 GPM.

Now all of a sudden I'm only getting .20 GPM and its taking forever to fill up. I am however still achieving 60psi on the Merlin so I'm not sure why my flow is so reduced. I hit the bypass switch to skip my home pre-filter so that it was just merlin booster and merlin unit itself and nothing improved.

What gives? Is my merlin sediment and membranes already clogged up after only a few weeks - month of running it?

Is my well flow just too poor to get good flow? I could have swore that my well tested at around 3 GPM when I bought the house. Not sure why I can peg 60PSI on the Merlin, but still have shitty flow/slow RO.

I have the below thing.. This is how I'm getting my GPM rating. Its supposed to clock the gallons that have passed through but now I'm not even sure its keeping track properly because its turning off.. I'm guessing due to low flow. When I was hitting .45GPM it would remain on..stating my flow on the screen and the gallons that have passed through it if I hit a button.

 

[SeaMaiden]

Have you tested the water coming out of the pre-filtration, to see if enough crap is being removed? My first thought was, "Insufficient pressure!", but you're saying you have enough pressure. I believe that RO requires 60psi as a minimum operating pressure, and I know that the pressure coming out of our well is 75psi, but I'm sure that's dropped by the time it passes through our whole house filter and to the RO/DI unit.

I still use a permeate pump, not a booster pump, in order to increase efficacy.

No, rereading your post, I think your membranes are clogged/saturated. Have you had a period of no rain, then rain recently? That fucks up our filtration system, which surprised me considering the depth of our well, but there it is.

Have you considered adding a permeate pump after the second filtration system, before the Merlin? Or is the booster in that position at the moment?

Also, does the Merlin have a back-flush feature, something that allows you to flush out the system?

 

[indianajones]

I had similar problems to you (450 ppm), but im on municipal water.my water pressure was at 22 psi before installing the booster and i can easily get it over 80 if i turn the booster up. if your psi sucks, you're not using the pressure booster properly.
my stealth ro 100 recommends 70 psi for max efficiency.

is there visible condensation on the outside of your unit after running it?

water temperature also makes a big difference in flow rates and efficiency.

 

[FlowerFarmer]

hmmm..

Poly pipe comes into the foundation from the outside well...it then goes into a Square D Pumptrol Switch (I imagine this is controller my well pump in the ground). There is a tee right after this that goes into large pressure tank for the house and a PSI gauge right after this that reads 50psi-70psi. I can hear the square D switch clicking at times so it seems to be working fine. From there it goes through a regular old sediment canister and then dispersed throughout the rest of the house. <-- Now this filter mucks up quick and is changed monthly, but I've turned the top to bypass it (just to try it quickly) and nothing really changes with my RO setup so I dont think that is the root of issue. I've also attached the Merlin in front of the house pre-filter right after this Square D Pumptrol.. I've got good PSI there (around 60psi) even without the booster pump, but nothing changes with my flow. I'm around 40 psi before going into the Merlin with no booster where I normally have it installed..(Booster brings it to 60psi). I don't have any attachment points 'in front' of this square D switch to test right off of the well.

I actually own 2 Merlins.. one with who knows what filters are in it and one with relatively brand new filters (like a month or 2 max). They both give me the same poor flow. I've opened the Merlin with the new membranes/filters and they still look pretty good...no discoloration on them or anything. Could they really have clogged in that short amount of time?

Still cannot figure this out. Literally have hooked it up all over the place in various order...I cant see how my membranes or filters would be clogged as I've never ran without a pre-filter for any real length of time....the occasional accident when I've turned on the booster pump without having the water turned on (very brief). I'm still getting 60psi out if it which seems to be whats its rated at . (5 chamber, variable speed, 3.0-4.0 GPM pump with 65 PSI pressure setting).

Perhaps it is just bad flow with my well. They say its been a relatively dry summer, but it has still rained lately. Seems to be heavy clay so maybe my merlin sediment filter before the 2 merlin membranes is clogged. I certainly don't want to spend the $$ on the 2 new membranes because I literally just did, but I guess I could try changing out that 1st one once again.

I guess something has to have clogged or changed with my well, but again my filters are pretty damn new and look clean still. Or perhaps my booster pump is bad even though it does appear to be getting me to 60psi??


IndianaJones,

I do get heavy condensation on everything when running the unit. Condensation will form on anything cold water is passing through...the cold line on the way to the RO.. the RO hoses and the housing itself. I figured this was to be expected with constant cold water meeting the room warm (mid 70s). Could this actually be causing my issues?


I'm at a loss. I don't think I can keep up RO at this rate (at least not without a lot more collection barrels and letting it run 24/7.... I've got 250gal of res that need topped up very frequently. I have been just filling the 55Gal in the evenings and just pumping it to each res as needed. Used to be able to flip my RO on when I got home and I'd have a barrel load before bed time... Now I'm not even getting a barrel load before morning.

My well water is 7.4 pH and flashes between .4-.6 on my Truncheon. Is it possible this is usable water for use with Head Recipe coco without RO? I need to send in for analysis and see whats in it. I'd love to do away with this RO headache all together and just run some pre-filters, but think my well is pretty bad and I've only even grown with RO. No experience with starting high ppm.

 

[SeaMaiden]

I tried to grow (coco coir) using my filtered well water and it did not go well at all. No back-flushing feature or component of the Merlin? I thought that 60psi is sufficient pressure to properly operate an RO unit. My well water is fairly cold, typically in the 50s.

 

[dalilguy]

I used a Merlin for a cpl years in one place that was on well water. I took it after the softener an never had any issues.. My best runs have been done in that old place. I'm currently on tap which comes out to .4 ec an the well at the same place comes out to .5 on my guardian. I have sent samples of both to be tested cause the well route will be a much cheaper way to go. Have it tested an see what all is in it an adjust accordingly. It is hard water but might still be usable I hated waiting around for my tanks to get full from the ro an now maintaining a few 100gal an 150gal rez it will take me a cpl days to get everyone full as I won't leave the to running at night.

 

[FlowerFarmer]

Hello,

No backflush - I think there might be an additional flush kit available, but I cannot afford any further $$ into RO making. I've already got thousand plus wrapped up into Tall Blue, Merlins, Membranes/Filters, Booster Pump, Electronic shut off kit, Flowmaster, etc.

Straight up sickening. I'm not running it wrong... as I've ran these for years in various locations. Its either just clogging rapidly (despite pre-filters..both home, tallblue, and the single in the merlin before the 2 membranes) or something else is wrong that is causing my issues.

My little GPM flow rate thing isnt even turning on now so I dont think I'm even getting .21 GPM anymore. Put the whole unit on a timer and ran it throughout the evening/night.. woke up to 25 gallons.. not going to cut it. The booster pump is 500w as well..

I've got some Veg+Bloom Hard Water formula samples.. Going to try 1 plant tester with it in coco and see how things look. Would be so nice to ditch the RO all together. Will look into sending my water away for analysis. Anything I need to request specifically? Whats the best way to go about this?

I wonder if just a regular old 1/4" 100GPD Stealth unit would work. I run these at other places and sometimes I wish I would have just not dumped the money on the 'big' gear and just ran the Stealth on a float switch around the clock. I could buy a new one every grow for what I've already dropped on double membranes for the Merlin a few times. Not sure if it would just low flow all the same.

Going to take apart the entire Merlin and see if I can get into the guts of it. Maybe something has clogged up in there...aside from the filters.

I WAS getting .45 GPM for a very brief period....that is what is driving me crazy.
Might haul my Merlin into the city and see what kind of flow I'm getting at another water source besides my well.


No softener at this location.
My pre-filter within the merlin is some green carbon pre-filter. Going to grab the actual Sediment filter (for non-chlorinated sources) when my hydro shop can get it in for me. Maybe the carbon pre-filter has reduced flow rapidly. I dont really need this, but this is what the shop got when I asked for a replacement pre-filter for my Merlin.

This is what I got:

This is what came with the unit originally.

Both are said to be fine. Your choice as to what to use.. but some reading revealed that if you don't have chlorinated water go with the actual sediment one.. Who knows. Worth a shot as these are sub $30.. vs. the 2 membranes it requires at $140/ea

Hopefully I'll get it sorted in a hurry.
One thing after another. I never stop accumulating hydro 'stuff'. My basement looks like a hydro-store spill over.

 

[dalilguy]

Various places will test your water for about 30-40$ I just found one through google..

If you are running coco an you feed with enough run-off you should be good. I was going to suggest stripping the unit down maybe a rock or something found its way in? Hope you solve it soon

 

[MIway]

Ff... Came from the stealth 200 to the merlin... Night and day improvement. Here's an outside the box, last ditch, crazy idea... I'm stretching for something... Maybe turn the unit upside down when you turn the supply on? My thought is that a big old air pocket is trapped and something weird is taking place with the pressure and preventing flow and not dislodging the bubble. It's a last ditch idea. I've got mine with the Grey portion lying flat with the tubes pointing straight up... Maybe I could see that happening...??? And iv tried both pre filters... The green carbon one has slightly less flow than the white fibrous one u have pictured. Can't see either slowing the flow like u r experiencing though. I recall there being a problem with the original membrane when the units first came out... But think that had to do with ppms, not flow rates. Curious to hear what is causing it when you figure it out. Gl man

 

[deacon1503]

what's your input water temperature? is your well on a 40/60 pressure switch?

 

[FlowerFarmer]

Gonna try running it on its end MIway...


Not sure what the intake water temp is.. pretty cold, but I'm thinking around low 60s. At least that is what it is in my collection barrel. Maybe a bit colder right out the ground.


deacon1503,
Yes. I'm pretty sure. The 1st thing right when the well line enters the basement is this thing.

Square D Pumptrol switch

right out the wall looks identical to this: Adjustments can be made to those 2 nuts holding down springs in the upper picture. I guess they are used to control "cut in" pressure and max "cut off" pressure. I've never messed with it, but it seems to keep me between 50psi - 70psi....however over at the Merlin (hooked to utility sink) I'm back down to just below 40 psi without the booster pump. I have tried it right after that pumptrol and I did get 60psi without the booster, but flow still sucked ass at .21 GPM

Too tired to mess with it tonight.. gonna open the merlin and check everything out tomorrow. New sediment filter coming in tomorrow as well.

Oddly.. I had it set to kick on before i got home from work with a timer. I ran some errands after work and the barrel was full when I got home. Gotta check the timer to see how long it ran.. pretty sure it was still slow.. but at least I got some usable water.

I'll keep you guys posted.

 

[deacon1503]

verify and install if not, atleast a 40/60. also, temp is a crucial part of RO output. check the conditions of your merlins rating. u need to get ur input temps up to the upper 70's. ur output will double guaranteed.

 

[deacon1503]

verify and install if not, atleast a 40/60. also, temp is a crucial part of RO output. check the conditions of your merlins rating. u need to get ur input temps up to the upper 70's. ur output will double guaranteed.

does ur tank have a pressure gauge? leave all faucets on and see at what pressure the well pump turns on and off.

 

[rives]

Hydroponic Research can do a water analysis for you, and will custom compound V+B for your water. I think that they require a minimum $100 order to do the custom stuff. Sounds like it might be a bargain in the long run.

 

[prune]

Gonna try running it on its end MIway...


Not sure what the intake water temp is.. pretty cold, but I'm thinking around low 60s. At least that is what it is in my collection barrel. Maybe a bit colder right out the ground.

jfc, you've spent close to a grand on your ro system and you neither read the instructions nor invested in a five buck thermometer?

RO efficiency drops rapidly with lower temps, and well water temps change seasonly in a lot of locations - both of which would explain your symptoms. Certainly if your res water is in the low 60's you are fighting this pitfall of all ro filters. Buy the gd thermometer and quit quessing...

 

[FlowerFarmer]

ah yes...

I've been focusing so much on intake PSI and filter health/order that I failed to acknowledge that the cold water was having that much of an effect on it. I guess I just automatically assumed something else as the unit was running at .45gpm one day and .21 the next.. without any drastic seasons change or anything. I mean.. I used this unit all last winter with zero issues.

Merlin instructions rate the outflow based on 77F intake water, but offers no solutions as to how to raise intake water temp.

What is the best method to achieve this temp coming out of my cold ground water source? I only have a cold water spigot, and know you don't want to connect these things directly to a hot line.

Is my best approach going to be to get a hot water line next to my cold water line and use a connection (see below) to merge the two together. Opening each a little to achieve a warmer water temp?

Something like this. Open the hot a little.. open the cold a little..and find the spot where I'm getting 77F out of the line?

Or is there a better solution as some type of on point inline water heater or wrapping my intake line feeding the RO in some type of heat tape, etc?

 

[FlowerFarmer]

ah yes...

I've been focusing so much on intake PSI and filter health/order that I failed to acknowledge that the cold water was having that much of an effect on it. I guess I just automatically assumed something else as the unit was running at .45gpm one day and .21 the next.. without any drastic seasons change or anything. I mean.. I used this unit all last winter with zero issues.

Merlin instructions rate the outflow based on 77F intake water, but offers no solutions as to how to raise intake water temp.

What is the best method to achieve this temp coming out of my cold ground water source? I only have a cold water spigot, and know you don't want to connect these things directly to a hot line.

Is my best approach going to be to get a hot water line next to my cold water line and use a connection (see below) to merge the two together. Opening each a little to achieve a warmer water temp?

Something like this. Open the hot a little.. open the cold a little..and find the spot where I'm getting 77F out of the line?

Or is there a better solution as some type of on point inline water heater or wrapping my intake line feeding the RO in some type of heat tape, etc?

 

[dalilguy]

I Know electric water heaters aren't expensive specially if you just need a small one. If u can't mix ur lines an get warm water some how it might be a route too go

 

[SeaMaiden]

Merlin wants your water at 77*F..?? Are you kidding? Whose water comes out of the tap that warm?

 

[rives]

I Know electric water heaters aren't expensive specially if you just need a small one. If u can't mix ur lines an get warm water some how it might be a route too go

Sounds like this might be the ticket. With the low flow rates from RO, you could set the thermostat at the ideal temperature on a 5-10 gallon water heater and stay in the ball park without an excessive addition to your electric bill.