RODI Water - 1 TDS

[kirkwood]

How much of an impact do you think RODI water with 1 TDS would have on SPS? I just got my 2 prefilters changed out and got my TDS back down to 0, but I probably used about 60 - 100 gallons of the 1 TDS for top off and water changes on my 120 over the 6 weeks or so... I have noticed lesser polyp extension on some millies..

 

[rdnelson]

I am no expert (but you knew that didn't you) but I will never allow anything but 0 TDS once I get back in. It just isn't worth it.


ARC....so nerdy our President breaks bones while bowling.

 

[heathlindner25]

Your fine, I wouldn't lose sleep over it.

 

[KrisDeitz]

Add some prime and use it

 

[kirkwood]

heathlindner25;922412 wrote: Your fine, I wouldn't lose sleep over it.

thats good.. I lose enough sleep over my 3 week old... ;-)

Now that my 2nd child is here I'm definitely seeing the difficulty in getting water changes done. Water changes are my means for maintaining Magnesium.. I tested yesterday and I'm down to 1225. Not devastating but I want to get back up to 1350, and my water changes aren't going to do that for me anymore. I'm toying with the idea of Epsom Salts for a cheap and temporary means to boost MAG. Any thoughts?

 

[rdnelson]

I used Epsom salt for a while. No I'll affects. But I heard that long term it can build up some unwanted stuff.


ARC....so nerdy our President breaks bones while bowling.

 

[jennm]

I wouldn't worry about 1 TDS. What's your incoming? Usually the goal is to remove 85% or better of the total dissolved solids, although most people freak out at 1 or 2 PPM TDS.

Jenn

 

[jennm]

That's what I was told by a Kent rep about 13 years ago, and they were the main manufacturer of RO/DI units for the aquarium trade at the time.

 

[curtismaximus]

I have been using water with 1 TDS for about 6 months now with no ill effects. However, just because it didn't affect my tank doesn't mean it won't bother yours.

 

[kirkwood]

JennM;922423 wrote: I wouldn't worry about 1 TDS. What's your incoming? Usually the goal is to remove 85% or better of the total dissolved solids, although most people freak out at 1 or 2 PPM TDS.

Jenn

I'm on the City water feed.. My incoming is at about 40 TDS.. I had been running the 2 prefilters for about 3-4 months so I didn't have a problem replacing them with a 1 TDS reading.. I felt like I got my money's worth out of them.

 

[rjrgroup]

Buckeye Hydro;922609 wrote: Rising TDS of the DI water isn't an indication that the prefilters need to be changed. This may help (from our FAQ's):

A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the usable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or both of the filters is beginning to clog.

Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove much of the chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons. Remember that all the water you process, both waste water and purified water, go through the carbon block.

Regarding your RO membrane and DI resin, use your total dissolved solids (TDS) meter to measure, record, and track the TDS (expressed in parts per million [ppm]) in three places: 1) tap water, 2) after the RO but before the DI, and 3) after the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1,000 ppm. Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block (collectively called “prefilters” because the treat the water before it reaches the membrane) do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see it is still approximately 400 ppm.

The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 90% (i.e., they reject 90% of the dissolved solids in the feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce purified water (a.k.a. “permeate”) more slowly, but have a higher rejection rate (96 to 98%). The lifespan of a RO membrane is dependent upon how much water you run through it, and how dirty the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the TDS in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce purified water more slowly as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the TDS in the RO water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, you know that your resin needs to be replaced. Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin “dirty” water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal.

Additionally, don’t forget to sanitize the entire system at least once per year, and wash and lube your housing o-rings with food-grade silicone grease every filter change.

Russ

Excellent write up!!!! A couple of points...
In the south, we typically have 40-50 TDS, Northerners contend with as much as a couple thousand.
While 1 TDS may be safe, it can be an indicator for additional contaminants penetrating the system. For example, organics are an immeasurable contaminant that a TDS meter won't measure. This is something to take in consideration when you see your TDS rising.The organics may actually be coming from your filters and not your supply water. It is always a good practice to replace all the pre-filters and DI resin at once to avoid cross contamination. On another note, %99 pure food grade Glycerin is usually available from your neighborhood drug store is a great way of "lubricating" the seals, o-rings or any threaded fittings like unions, bulkhead seals and true union ball valve end caps. Use sparingly but it is fine for our purpose and is priceless when servicing systems. If a RO/DI is properly maintained, the RO protion can last for 10+ years providing the filters are replaced and the RO is flushed daily or at the very least weekly.
Randy

 

[mc524]

I placed a T inline prior to my DI cartridge. Then a ball valve off of that T. This is my RO water fill line that i use for storing drinking water, but mainly i use it to drain off (clear the line) of any water that was sitting in the RO membrane. Sometimes this water will show 50 or so TDS. So i open the RO valve until that number is under 10 TDS going into my DI cartridge. Once its there, i close the line, then open the DI valve for a few seconds. At this point my TDS meter usually reads 0 on both sides up to about 3-0.
I have 2 DI cartridges sitting standby, along with DI resin from BRS. So i will be refilling myself from now on instead of buying new. I also plan to add a booster pump here soon.

Sent from my XT907 using Tapatalk

 

[acroholic]

If my TDS were rising, my first thoughts would be my DI resin, not anything else. RO membranes last for 5-10 years around here. Our Input TDS in this area is 35-40....almost soft water to start with. Mine is always around 38.

I change my prefilters out about every 6 months, and my DI resin at the year mark, and I always have 0 TDS water.

 

[mc524]

Thanks!
As of right now it is all manually operated. So normally its on to fill 10gal for mixing station. I do have that setup with a float and the check valve. However, i turn it off and normally fill a 1 gallon jug to add to my Top Off container. After that, it might get used a day or two later to refill that gallon jug. So the creep is understandable. I get pretty good amount of time out of my units filters.

Sent from my XT907 using Tapatalk

 

[acroholic]

If my TDS were rising, my first thoughts would be my DI resin, not anything else. RO membranes last for 5-10 years around here. Our Input TDS in this area is 35-40....almost soft water to start with. Mine is always around 38.

I change my prefilters out about every 6 months, and my DI resin at the year mark, and I always have 0 TDS water.

 

[acroholic]

That is what the OP states in his first post. It is his RODI water he is referencing.

 

[kirkwood]

Kirkwood;922580 wrote: I'm on the City water feed.. My incoming is at about 40 TDS.. I had been running the 2 prefilters for about 3-4 months so I didn't have a problem replacing them with a 1 TDS reading.. I felt like I got my money's worth out of them.

I might be wrong and may have been running those profilers for 6-9 months. Regardless I changed them out and am now back to 0 tds. This time I made sure to record the date of the swap in my tank log book. I will keep up with the semi annual changes.

 

[acroholic]

Kirkwood;922721 wrote: I might be wrong and may have been running those profilers for 6-9 months. Regardless I changed them out and am now back to 0 tds. This time I made sure to record the date of the swap in my tank log book. I will keep up with the semi annual changes.

The new prefilters/filters could be catching that 1ppm TDS reading you were seeing. It is not necessarily the DI resin as I suggested. 1 ppm TDS is not a lot of material.