Spend the extra couple $$ on a Spectrapure Select series 99% membrane and an untrimmed capillary tube flow restrictor which you then adjust for your exact conditions and you will be amazed at the difference.
Attempting to fix RO DI excessive consumption
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I usually buy directly from Spectrapure so I know I am getting the freshest products. I do check Marine Depot and Premium Aquatics though as they sometimes have sales and free shipping.
You want this membrane
http://spectrapure.com/FILTERS-MEMB...-SpectraSelect-Plus-Tested-90-GPD-RO-Membrane
And a 90 gpd untrimmed capillary tube restrictor.
You want this membrane
http://spectrapure.com/FILTERS-MEMB...-SpectraSelect-Plus-Tested-90-GPD-RO-Membrane
And a 90 gpd untrimmed capillary tube restrictor.
Yes. It will come with instruction on how to check your waste and trim the length based on your findings or you can find the instructions on like page 8 of any of the Spectrapure owners manuals available for download on their website. That way you can fine tune your system unlike the fixed restrictor that never seem to be quite right. RO/DI is almost plug and play but a few extra minutes doing things like disinfecting the system annually, flushing each replacement filter systematically on installation, fine tuning the waste and monitoring your temperature pressure and TDS go a long way towards lowering your operating cost and improving for final water quality.
@AZDesertRat, Thanks for the help. I just placed my order for those 2 items and I will be reading through some of the user manuals to see what they say. How did you initially find out about this stuff? Is it something to do with your line of work or do you just really like water purification?
Thanks!
Thanks!
I have been a certified water treatment plant operator, supervisor and manager for 40 years. After retiring from municipal service I now am employed by a top 10 water/wastewater environmental firm doing consulting now. Water is pretty much all I have ever done and carries over to my hobbies.
I am going to post the link here for future reference. Wasn't too bad of a read and really helped me to understand my unit a little better actually.
https://spectrapure.com/manuals/memRepGuide.pdf
Based on the calculations there looks like a 90GPD unit should give me the following output:
PCF = Line Pressure (in psi) ÷ 60 (Pressure Correction Factor) [55/60 = .91666667]
TCF = (See chart in link) 55.4 F = 0.684
Expected GPD = Rated GPD × PCF × TCF
~56 GPD = 90GPD x .91666667 x .684
1 Gallon = 128 Ounces
56 GPD / 24 hours = 2.3 Gallons an hour or 294.4 ounces an hour (2.3 * 128)
So I should theoretically see somewhere around 294.4 ounces/60 minutes in the hour = 4.9 Ounces in 1 minute... That is assuming I did all of that correctly. Now I know what my potential target is assuming that I get my waste/water ratio at the 4:1 mark as the manual suggests once the flow restrictor shows up along with the membrane.
https://spectrapure.com/manuals/memRepGuide.pdf
Based on the calculations there looks like a 90GPD unit should give me the following output:
PCF = Line Pressure (in psi) ÷ 60 (Pressure Correction Factor) [55/60 = .91666667]
TCF = (See chart in link) 55.4 F = 0.684
Expected GPD = Rated GPD × PCF × TCF
~56 GPD = 90GPD x .91666667 x .684
1 Gallon = 128 Ounces
56 GPD / 24 hours = 2.3 Gallons an hour or 294.4 ounces an hour (2.3 * 128)
So I should theoretically see somewhere around 294.4 ounces/60 minutes in the hour = 4.9 Ounces in 1 minute... That is assuming I did all of that correctly. Now I know what my potential target is assuming that I get my waste/water ratio at the 4:1 mark as the manual suggests once the flow restrictor shows up along with the membrane.
Which is exactly where I pointed out your flow should be early in this thread. I didn't do the long calculation with TDS considered and I rounded the temperature down. I recommend everyone use the worksheet you linked to to find out how their system is really working.
I hope everything works out well for you and am here if you have any other questions.
I hope everything works out well for you and am here if you have any other questions.
As a quick update for anyone following this or referencing it in the future. My new spectrapure membrane showed up this evening. I installed it and followed the instructions to install it and the new flow restrictor. The new membrane put out 4 oz of RO water in 1 minute and 19 oz of waste water so I am almost a 5:1 ratio. I let it run for about an hour down the drain and then put my DI resin back in. The new TDS numbers are pretty awesome. 3-5 TDS into DI chamber 1 (down from the 40's) and I am 0 into chamber 2 and 0 out. Thank you so much for all of the help everyone!
Quick update. I spoke with Spectrapure's technical support about my 5:1 ratio and they had me "choke" off my waste line to create back pressure on the new membrane. I did this by putting a 1/4" ball valve about 20" off the membrane waste line (so as not to interfere with the capillary tubing). I slowed the waste down to about 14oz/min. Production water is still at 4oz/min and after the RO unit had been running about an hour (refilling all my reserviors) TDS was 1 coming out of the membrane!! Simple amazing. Should really help me save some money from not having to replace DI resin monthly. I am hoping that it helps eliminate this slimy mucus I get on my sumps surface as well.
So I have been noticing a slimy build up on the surface of my sump again which is what lead me to everything above. I tested my TDS and found the following:
- Pre-membrane TDS: 164
- Pre DI resin #1 TDS: 18
- POST DI resin #1 TDS: 18
- POST DI resin #2 TDS: 18
I measured the temperature of my water going into the RO unit and found that with it starting to get warmer that the water temperature increased so my waste to production was 1:2. I unchoked my waste line and am now at 1:4 ratio (output: ~140ml, waste: ~550ml) which seems inline with the calculations. I even compared my new results with calculations from the manual and they seem to be on. So my question is
1. The DI resin is 3 1/2 months old why isn't it changing color? And does it need to be replaced?
2. Why is the TDS coming out of the membrane at 18?
I purchased a handheld TDS meter and have been double checking the inline TDS numbers with the handheld numbers and they are about 2tds apart so it seems like the numbers are pretty accurate.
Thoughts?
- Pre-membrane TDS: 164
- Pre DI resin #1 TDS: 18
- POST DI resin #1 TDS: 18
- POST DI resin #2 TDS: 18
I measured the temperature of my water going into the RO unit and found that with it starting to get warmer that the water temperature increased so my waste to production was 1:2. I unchoked my waste line and am now at 1:4 ratio (output: ~140ml, waste: ~550ml) which seems inline with the calculations. I even compared my new results with calculations from the manual and they seem to be on. So my question is
1. The DI resin is 3 1/2 months old why isn't it changing color? And does it need to be replaced?
2. Why is the TDS coming out of the membrane at 18?
I purchased a handheld TDS meter and have been double checking the inline TDS numbers with the handheld numbers and they are about 2tds apart so it seems like the numbers are pretty accurate.
Thoughts?
When you make RO/DI how much do you make at a time and how often? What is your water temperature and have you ever run hot or even blended or tempered water through it?
How long had it been running at the greatly reduced waste ratio? The membrane may be plugged or fouled with built up solids since it was not being well flushed via the waste. Watch it over the next few weeks while making larger batches of water and see if it improves.
What are you using for sediment and carbon block filters, how old are they and what is your pressure at the membrane?
How long had it been running at the greatly reduced waste ratio? The membrane may be plugged or fouled with built up solids since it was not being well flushed via the waste. Watch it over the next few weeks while making larger batches of water and see if it improves.
What are you using for sediment and carbon block filters, how old are they and what is your pressure at the membrane?
I make 10 gallons at a time every Saturday. I did push 15 gallons through it this weekend to let it run for a bit while I was re measuring the levels.
Water Temp: 62F - 63.5F is what I have been observing over the last week. I have never ran hot or blended water through it. Always had the same water source.
I'm not sure how long it had been running at the 1:2 ratio.
12/10/15: Put new membrane and flow restrictor in place
12/30/15: Replaced pre filters with:
(1x) 0.2 Micron (Absolute) ZetaZorb® Sediment Filter Cartridge 10-inch - SF-ZZ-0.2ABS-10
(2x) 0.5 Micron Carbon Block Filter 10-inch - CF-0.5-10
Then the first part of this year (jan) I replaced both DI resin cartridges with BRS color changing resin
Water Pressure: 50psi
I was going to measure my membrane rejection rate to test for fouled membrane but I don't have a hardness test. If things don't improve over the next little bit I may get one so that I can see what my rejection rate is.
Water Temp: 62F - 63.5F is what I have been observing over the last week. I have never ran hot or blended water through it. Always had the same water source.
I'm not sure how long it had been running at the 1:2 ratio.
12/10/15: Put new membrane and flow restrictor in place
12/30/15: Replaced pre filters with:
(1x) 0.2 Micron (Absolute) ZetaZorb® Sediment Filter Cartridge 10-inch - SF-ZZ-0.2ABS-10
(2x) 0.5 Micron Carbon Block Filter 10-inch - CF-0.5-10
Then the first part of this year (jan) I replaced both DI resin cartridges with BRS color changing resin
Water Pressure: 50psi
I was going to measure my membrane rejection rate to test for fouled membrane but I don't have a hardness test. If things don't improve over the next little bit I may get one so that I can see what my rejection rate is.
Your rejection rate is calculated using the tap TDS and RO only TDS.
Tap-ro, divided by the tap, and that result multiplied by 100.
Tap-ro, divided by the tap, and that result multiplied by 100.
Hard to say for sure. If you have enough containers I would try and make 25-30 straight and monitor the RO only TDS every so often and making sure the waste ratio is at least 3:1 to 4:1.
I have 20 gallons in containers so I filled those up. Right around the 20 gallon mark is when I had a chance to test everything.
RO TDS: 8
Waste: 550ml
Production: 150ml
Ratio: .27 so in a good range
Water temp: 59.9f tonight
I ordered some new DI resin and am going to try it how you recommended. I am seeing 8 going into DI chamber 1 and 18 coming out so it needs to be replaced. I'm hoping that new DI canisters solve my problem.
RO TDS: 8
Waste: 550ml
Production: 150ml
Ratio: .27 so in a good range
Water temp: 59.9f tonight
I ordered some new DI resin and am going to try it how you recommended. I am seeing 8 going into DI chamber 1 and 18 coming out so it needs to be replaced. I'm hoping that new DI canisters solve my problem.
Looks like the rejection rate is improving. Definitely replace the DI ASAP. With those readings I would just remove the DI and use RO only until you get the new cartridges. When DI starts to exhaust it releases weakly ionized substances like nitrates, phosphates and silicates, things which don't register well on a TDS meter so the effluent is probably worse than you imagine. That 18 could really be much higher if measured by electrical conductivity.
Looks like I made it almost 2 months on this DI resin. I measured 1ppm tonight so I will be following your advice AZDeseretRat and will be moving the 2nd DI cartridge to slot #1 and putting a new one at the end. I'm also going to replace pre filters this week.
