Tds

[Reefpro]

Someone help!!!
I have been battling pale SPS and thought I would test my TDS from ro/di unit today... It read 78. Yes that's right 78 parts per million. I just changed both membranes (150 GDP each) and the DI resin is bout 6 months old. My water comes from a well and my DT is 250 gallon with LEDS. Here' s the kicker........my tap water had almost the identical reading for TDS. I used two different meters to rule out equip error. What gives, can anyone possibly make sense of this? Any thoughts or help is greatly appreciateda

 

[NanaReefer]

Change your DI resin asap.

 

[Reefpro]

Will change di resin In the am,, but weird that the membrane isn't catching any of the TDS, since tap water and output of ro/di unit is nearly identical

 

[trido]

Sounds like your RO membrane is shot along with worn out DI resin. I've never heard of that high of TDS in the Pacific Northwest.
I dont even have an RO membrane right now and my worn out DI brings my TDS from 24 down to 3 without an RO membrane at all.

 

[Reefpro]

Would it seem odd to you that the membrane is only two months old and already shot???

 

[trido]

It would seem very odd. My next guess would be that some of the connections are plumbed in backward. Are you positive that the waste water line and pure water line from the RO unit aren't backward. Also, the pressure balance valve could have gone bad. I'm not at all good with RO units though. Just throwing out ideas.

 

[kau_cinta_ku]

where are you testing the TDS from? the holding container or stright out of the line?

 

[kau_cinta_ku]

if testing from the holding container that could be the reason the TDS is high, RODI water is like a magnet to air born particles, as long as the TDS comming from the line reads 0 then your fine.

 

[AZDesertRat]

Photos would help.I know from experience the 150 GPD membranes have troubles and som vendors quit carrying them due to not living up to rejection rate claims. I owned one myself but was lucky enough to get a good one. Check your tap water TDS, RO only TDS and RO/DI TDS, also for this exercise check your waste TDS, the lines amy be switched somewhere. What is your exact measured waste ratio? Water temperature and water pressure? It takes a minimum of 65 psi to operate a dual membrane system and hopefully you have not bought into the misinformation that dual membranes are a water saving device, they are not and it is even more important you keep the waste ratio at 4:1 since you are sending the concentrated brine from the first into the second.

 

[Reefpro]

I will ck this in a bit. I just woke up.....work graveyards. The unit is a hrydrologic triton . I stand corrected its is a 200 GPD system. I have not changed or unhooked any of the lines and worked great until I repalced membranes and got on we'll water.

 

[Reefpro]

Water is 65 degrees and the inlet pressure is 80 psi. I use a booster. This set up supplies both my too water that goes to float valve in sump and fills up 55 gallon barrel when I open valve to the barrel on water change days.

 

[AZDesertRat]

What are the four TDS readings and your exact measured waste ratio? What membranes did you buy, hopefully they are not the Dow Filmtec 100 GPD, they are the worst possible choice you can buy since they are only 90% rejection rate nano filters and not 96-98% RO membranes.

 

[Reefpro]

Uggghh.. They are filmtec 100 GPD membranes purchased from H2Ofilters.com. Trying to find tds meter now. But I know it was around 78 after di and 83 at tapa

 

[AZDesertRat]

The most important TDS reading is your RO only since it does most of the work. You use the tap water TDS and RO only TDS to determine the rejection rate or removal efficiency. If its not good the DI will not last no matter what resin you use or how long the contact time is. 100 GPD Dow membranes are rated by the ANSI/NSF as "Pool and Spa Use" since they are not considered a RO membrane. I would never recommend them to anyone and most vendors will do everything in their power to persuade you against them. The reason being for every 2% you reduce the rejection rate (90% versus 96-98+ or higher with some mebranes) you cut your DI life in half. So a 6 to 9% improvement with beter membranes would make your DI last 4 or 5 times longer and get you true 0 TDS treated water. The other question you have not answered is the measured waste ratio, this is a critical number since it is the constant flushing while in operation that keeps the membrane(s) functional, cut it down and you do not have the volume or velocity to carry the concentrated brine away from the membrane so it eventually fouls the membrane and it fails prematurely.

 

[Dustin1300]

Sounds like a couple good membranes and new flow restrictor is in your future. DesertRat helped me out when I doubled my membranes and the 150 GPD I got from BRS were JUNK. Ran to PA that following day and picked up a couple Spectrapure 90 GPD membranes and my TDS has been 2-4 after membranes and running about 95-100 PSI and get about 177 GPD between the two. These will pay for themselves in saved DI!

 

[Reefpro]

Ok the results as tested correctly

Ran ro/di for 60 seconds and tested. 16
Checked after membranes only. 16
Tap water 106

Changed sediment filter and replaced DI resin TDS after ro/di is now 1.
I do not know how to test discharge rate but the box for unit states the ratio is 2:1

I am ordering new spectra pure membranes in a few minutes. Should I get the 100 GPD as that is what the flow restrictor is rated for?

 

[AZDesertRat]

You will want their 90 GPD membranes. Looks they they only offer two versions now, the standard 90 which is specially treated and batch tested and averages 98+% rejection rate but is not guarateed to do so Standard 90-GPD RO Membrane , history says it does though. They used to have their Select series 90 GPD which again is specially treated but it is then individually hand tested and guaranteed in writing to be 98+% rejection rate but I don't see it on their site and finally they have their newest hand tested membranes that are guaranteed to be 99% rejection rate NEW 99 Percent Rejection SpectraSelect Plus? 90-GPD RO Membrane . You will also want their matched 180 GPD flow restrictor here: Standard 180-GPD Flow Restrictor. The flow restrictor will get the waste up where it needs to be, around 4:1, but you will adjust it according to their included instructions once you have everything installed. If your RO/DI is already at 1 either your TDS meter is dirty, out of calibration or your DI resin is outdated or not stored properly. Resin has a short shelf life so you should not order any more than you can use in couple months time, store it vacuum sealed with a little moisture in it and place it in the back of the refrigerator so it is cool and out of direct lighting. It quickly loses its cation and anion electrical properties if not packed and stored properly or if it has been opened and not resealed well. The membranes you have are only about 85% efficient at 106 tap and 16 RO only, not very good at all.

 

[Reefpro]

What affect will this have in SPS zoas and LPS?

 

[AZDesertRat]

There is no standard answer except water is the single largest ingredient in a reef and everything depends on its quality and its stability. The better membranes will give you longer DI life, better water quality and a lower cost of ownership since the DI will last many times longer. Without knowing what your specific TDS is made up of no one can give a black and white answer.

 

[Reefpro]

Man you have been a wealth of knowledge. I just ordered two spectra pure select 90 gpd membranes and a 180 flow restrictor. 119 $ total cost
Can I pull the old restrictor out of flush valve or how does that work?