R.o Units

[H.crispa]

I love my RO unit! I recommend everyone get one! I use mine for aquarium, brewing, drinking and cooking. I bought mine over 10 years ago when I was keeping discus and breeding angelfish. I looked at it as an investment and I had much greater success (Higher hatch rates, better survival rates etc. because I was on St. Albans city water at the time.) Without going into all the details of S.A. city water and how the process it etc., it is normally around 350ppm TDS and a pH of around 7.6. I bought "the best" unit I could find. An Aquafin AF100 at a pricetag of close to $900 for a 100gpd unit. It has never let me down and the maintenance has been nearly non-existent. 10 years later, my product water still tests out at around 3ppm-- the same as when it was new. I still have the same membrane. Never replaced it.

My thing is, it has never produced the rated 100gpd! I knew this was the case when I bought it b/c of previous experience with a smaller unit, so I bought a unit far in excess of what I figured I'd actually need. Why is this? Well, it supposedly has to do with how the membrane capacity is rated. The higher the pressure, the more efficient the membrane is. The lower the density of the water, the better it performs. Cold water is more dense than warm water. How much I have no idea-- if you really care, do a google search and calculate the density at a given temperature based on known chemistry formulas. I don't care. I got the basic gist.

60psi @ 70 degrees F seems to be the parameters at which RO membranes are rated. Currently, my water pressure here at the house is about 90 psi and in the summer, the temperature is around 70. In the winter, the temp is a lot less and my unit does indeed, produce less water per day in the winter. However, even in the summer, when the temperature is right on the money and the pressure is far in excess of how the membrane is rated. However, I still never get 100gpd. Any thoughts on that?

 

[grendl]

I am paying for mine (finally) on Friday... I am getting a unit from Bryan at Purelyh2o, a referral from the vendors thread. I am pretty stoked, this is a major obstacle out of my way.

I to have wondered about the GPD rating on these, & if they can be effectively acheived. If you are meeting the minimum PSI then I wouldnt think it would impact the end result of the "good" water output, especially if the water temp is right (which in your case it is, in the summer). I figure the waste water would be increased with more PSI, or colder temps, but the good water would remain the same.

Do you have a valve to control the water flowing into your filter, that could drop the PSI coming in? I doubt ti would make a difference, but if thats the only thing thats not in alignment, then it seems that it wouldnt hurt to try to adjust it, just to check the results.

With 10 years of RO/DO under your belt, I would assume that you are taking into account the amount of water flowing out to your icemaker & your drinking water.... with a 100 GPD unit, you are producing around 4 gph, which isnt a huge amount, & it could be impacted if you have a family drinking alot of water.

Another thing to consider is that your membrane might be filtering all the crap out still, but it might be somewhat clogged after all that use. It likely wouldnt hurt to spend a few $$ on a new filte, to see if that would make a difference?

 

[purelyh2o]

Hmmm.

Hmmm.

One of the things that is frequently overlooked on an RO system is the waste to product ratio. There have been alot of changes and improvements made over the years regarding the accuracy of the flow restriction provided to the membrane. I will give you a project to do and when you are done come back and give me the answer and we can go from there.

Check you waste to product ratio.

By using 2 glasses of the same size or measuring cups.

First fill the first glass with product water for a total of 30 seconds and mark the fill line.

Repeat the same with the waste line and mark the fill line.

The answer that I need is how much waste verses product you are producing

2/1 or 3/1 etc..
The waste will be higher than the product water I just need to know exactly.

 

[richfavinger]

RO membrane performance is highly dependent on line pressure and water temp.
Most membranes are rated GPD @ 50psi and 70*F or so, water temp, any thing less then that, you cut in to the GPD. But as mentioned above, the key is ratio of preferred 3:1. Check your RO manual and the flow restrictor size you need.

A booster-pump can help give you most times 60psi, and note that you will get better threw put in warmer weather then colder. In winter my rate on my 90gpd unit is cut by about 1/2.

I use the SpectraPure 2000 90gpd 5-stage RO/DI unit. Love it! SpectraPure is truly one of the best! I'd highly recommend them to any one!

Rich

 

[purelyh2o]

??

??

His parameters are close to perfect.

He doesnt need a booster pump at this point. He has already achieved 70 PSI without one and his temp is only 5 degrees under perfect.

H.crispa, If you can just get me those readings I will help you fix the issue.


Bryan Crenshaw

 

[grendl]

Speak of the devil!!!! *we're not worthy!*

 

[purelyh2o]

Whats up buddy!

 

[H.crispa]

You know, I did think of looking att the waste to product ratio but never got around to actually measuring it.

Thing is, if I restrict the wastewater, will my membrane "plaque-up"??

 

[purelyh2o]

Yes and no

Yes and no

The problem is that you have really good parameters and have never produced the correct GPD rating. This can only be 2 things. Either your system is under restricted or you dont have a 100 gpd membrane. Im guessing that when you test your ratios you will be around 5 or 6 to 1

Let me know

 

[grendl]

So what you are saying, is that instead of pushing the water thru the membrane, its just flushing it out the waste line, because its the easy way out? This would be fixed with a restrictor valve on the waste line, to increase dwell time over the membrane, forcing more thru it?

 

[purelyh2o]

Exactly

Exactly

Unfortunately given variables in the source water there is no perfect way to tune the restriction in the system to be be perfect for every situation. A system that works perfect in one home may be shakey and wasteful in another. There are many factors, some mentioned above and others including the overall density in total dissolved solids in the source water that will cause a harder time permeating the membrane and ofcourse following the path of liest resistance (the drain). The most simple answer to this is to remove the flow restrictor all together and add a more personal touch . The addition of an adjustable flow restrictor allows you to tune the system in to the parameters you are facing in your home and will allow the system to work to its full potential. Most people have no idea just how important the flow restriction in the system is until they remove it all together by accident and realize they are no longer making water

This should be the answer and usualy is in situations like this.

 

[H.crispa]

It has been a while since I tested my output. My product to waste ratio is 1 to 1! My product is far in excess of 100 gpd! According to my calculations, 100/24=4.16 gph. 4.16/6=.69 gallons every ten minutes. I am producing 1 gallon every ten minutes. I do not know when this happened but once again, I should have re-checked before I posted.

By my calculations, I'm making 144 gpd. I have nothing to complain about!

Here are some pics of my wonderful unit:

I'll bet you never thought I'd post pictures of my unit huh???

 

[H.crispa]

In the next to last pic, what is that gizmo? Is that some sort of adjustable resistence thingamabob?

 

[purelyh2o]

OLD SCHOOL...lol

OLD SCHOOL...lol

That is an old school Auto shut off kit.

Now we might have another problem. Can you test the TDS at the output and see what it is?