DI water / Filtration / Water Softener for coolant water?

mhajicek · Jan 4, 2019

After running for three years without problem I noticed a dramatic mineral buildup and rust problem in our machine. Coolant concentration is correct, so I'm suspecting hard water. What do people use to limit mineral content in their coolant water?

Thanks!

Generic Default · Jan 4, 2019

Weird these posts always come up right when I'm considering them too. I just bought a cheap RO filtration unit on Ebay a few hours before you posted this. It says 50 gallons a day max, the thing cost just under 80 dollars total. I wanted to start with fresh, clean water when I put in the Blaser clear coolant in a few days.

Since 50 gallons a day is a trickle, I expect to hook it up under the sink and have it trickle into a big plastic tub, which I'll mix the coolant in and dump into the machine for the first charge after cleaning it.

BTW I bought Mobilcut 100 coolant to start in the machine, it was problematic from the start and I spend way too much time cleaning my filters and dealing with coolant problems because of it.

Pete Deal · Jan 4, 2019

It depends on how much coolant you need to make. I make 5 gal at a time. This I made from about $100 of parts from ebay, mcmaster, and some scrap metal. It consists of a particle filter, a carbon filter, an ro membrane filter, and a little crappy in line tds meter. It takes a few hours to fill a 5 gallon bucket. Works well so far.

13engines · Jan 4, 2019

After nearly 15 years of buying distilled water at 89 cents a gallon, I finally bought an RO/DI system from a local aquarium supply. Works great. It cost me a few hundred to get the thing fully going. I think I got a 90 or 100 gallon a day system but added a pump to get the pressure up. They work a lot faster with higher pressure. It all flows into a ten gallon tub with a float switch. I had that tub, which includes a pump, sitting around since the beginning of time, and finally found the perfect use for it.

You get all kinds of answers around here about what type of water you need for coolant. All I can say is using distilled and RO/DI water has kept my coolants lasting for practically forever with no smells and no troubles.

Generic Default - make sure you read the literature for your new coolant. Many times on the initial fill you want to use either all hard water or at least a percentage of it.

Dave

TDegenhart · Jan 4, 2019

Whatever you do, don't use copper or iron pipe. Plastic only with di-ion.

Tom

SND · Jan 4, 2019

I'm starting to add RO to my machines now too, used tap water for the fill up though but with my softener I'm worried about the high salt content adding up.
Been buying/refilling the 18.9L jug for now.

For you guys with the RO system, does the RO membrane get backwashed/flushed or anything, or it just collects the dirt until its clogged right up?
I always heard RO wasted like 10x more water than it produced, so, kinda wondering.

DavidScott · Jan 4, 2019

I got an RO system off of Ebay a few years ago. It is rated at 150 gallons a day for around $130? Water temp and pressure make a hugh difference in how fast it works and how much water it wastes. If I warm the water, or set the unit in the sun in the front yard, I can fill a 5 gallon jug in 45 minutes, cold it can take 2 hours at 55 psi. No complaints yet. I went with the size I got because the bigger filters were not that much more $ than the smaller ones.

Yes you backwash them occasionally. Yes they waste a lot of water but over half the year I do it in the front yard and let the waste water the grass. Depending on temp and pressure the waste can be 3x so not that big a deal.

13engines · Jan 4, 2019

I back-flush my RO/DI system for a few minutes before running it each time. I'd have to look at the instructions again to see what the recommended time for back-flushing really is. I browsed ebay for a system and then found Bulk Reef Supply locally so went with them. Always like to keep things close to home if possible. Bulk Reef have created a bunch of Youtube videos that tell you everything you'd ever want to know about RO/DI systems. Even the good reasons why if you don't have descent pressure to use a boost pump as I did. I think it had a lot to do with efficiency. (Like wasting less water.) My system runs at nearly 90 psi if I remember right.

Dave

adama · Jan 4, 2019

Honestly theirs little gained from using DI. If you can get bellow 50PPM with RO theirs no benefit in going purer, the waters just going to pick metal ions up from the swaf - the machine to get back to about 50PPM. Remove the chalk and have a neutral PH water largely free from dissolved solids - gasses is all you need.

Better RO setups have a bypass around the flow restrict-or to flush the membrane. Putting back pressure on the membrane is not really a good idea, there not a filter per say and back pressure is not going to work like it does with a typical filter material.

Chlorine is hard on most RO filters and is also something you don't want in your coolant as it promotes rust and does nothing to stabilize the coolant emulsion. Hence theirs a lot to be said running it off a well. Other option is rain water and also air con drain water, both are pretty pure if collected with care and just a basic particle filtration.

Its the minerals that build up in the tank that most stuff lives off and also when they get high enough cause the emulsion to crack.

Pete Deal · Jan 4, 2019

I used to work at a pharma plant and we had a guy there that was pretty good with water systems. What I wound up with is based on what he said I needed. The carbon filter is first and removes chlorine which I was told is not good for the ro membrane, particle filter is next to remove the carbon particles, then the ro membrane cartridge. No DI bed on mine. The water off mine reads about 5ppm. I bought a cheap inline tds meter and a pen type one. Both agree pretty well.

I'd like to get some chlorine test strips to monitor the chlorine level coming out of the carbon bed.

I like idea of running it into a plastic tank with a float valve to shut the whole thing off when it fills.

13engines · Jan 5, 2019

I've also heard about DI being more than enough for coolant. My system has a bypass valve to skip the DI filter. I mostly turn it on or off depending on my mood for that day. The ppm gauge does drop to 0 or nearly so with it on.

DavidScott · Jan 5, 2019

adama said:
Its the minerals that build up in the tank that most stuff lives off and also when they get high enough cause the emulsion to crack.

I have two coolant systems in my shop. One is for metal and one is for stone and ceramic. I have not changed the stone coolant in 17 years and since I machine a lot of calcium carbonate the water is as hard as it can get, I have travertine forming in my coolant tanks. There is something living in there but it never gets out of hand, just a little slime along the sides. My metal coolant is well taken care of. I remove the oil, filter to 5 micron between the machine and coolant tank, run an air bubbler for 15 minutes every 6 hours, use a full synthetic and top up with clean RO water. 2 months after I desiff everything and put fresh coolant in I have something growing in my metal coolant, it loves it. To keep it in check I have to use a biocide every 2 weeks, and that is just to keep it in check, not totaly get rid of it. Whatever biohazard I have loves coolant concentrate, not minerals.

My RO system says to backwash every 3 months for 15 minutes.

adama · Jan 5, 2019

David everyone's well water or even municipal water is different, salt - mineral build up depending on what it is will cause most coolant emulsions to brake down. Chlorine comprising salts especially break coolant emulsions. That said some coolants are far more immune to hard water than others.

More than possible the bugs in the metal one are not eating the coolant but the actual metals themselves and braking down chlorine's and sulfates in the concentrate in the process and such in the coolant to make the stench. The higher alkalinity of the stone tank is probably a completely different "eco sytem" of bugs eating a completely different diet. Being carbonate stones, more than possible there farts are just CO2 and hence odorless to us humans.

Might be worth trying standing a large lump of carbonate based rock in the metal tank and see if that helps neutralize - change the environment enough to kill your problem bugs. Also worth running a PH test between the 2 and seeing what you have. My guess metals acidic, stone alkaline.

DavidScott · Jan 5, 2019

Well water so no chlorine from it, and no stench from the old coolant. Considering the "coolant tanks" used by the stone processors who knows what bugs I have brought into my shop with all the different stones I have machined over the years.

I definitly need to test ph and will try some marble in the metal tank, it can't hurt at this point.

CarbideBob · Jan 5, 2019

So, just a plain ole bag salt water softener and big 5 micron cartridge filter on poopy well water won't work?
Is RO really worth the hassle and cost? Is the life that much better or is it a feel good thing?
With maintained coolant concentration and PH what kind of difference?
Used coolant disposal for me is a big no-no. Carbide grinding, cobalt, hazardous waste fee.
Bob

Pete Deal · Jan 9, 2019

I only went with RO because I called the people who make my coolant (Trim E206) and that is what they said to do. It makes sense to me that by adding hard water to make up all the time would result in the minerals in the water to increase each time which seems like it would be bad after a point.

CarbideBob · Jan 9, 2019

For some reason I place my trust in coolant sales people below that of tool salesmen.
That is a very low bar.
Bob

adama · Jan 10, 2019

^ I agree, but from a basic chemical point of view all softening does is replace the calcium with sodium, still just as much minerals in there, just a different kind. RO removes that mineral concentration.

I would not sweat lots of mixed bacteria, you need a eco system, not a monopoly, because single organism only will stink, either as it eats what its eating or as it dies and something eats it, Secrets in having a stable biological food chain in there that does not cause odour or eat the machine - eat you. The natural pond of some stone masons wet systems is probably a great place to find a balanced eco system of bugs to colanise your tank, add in the stone waste neutralizing the acid stagnant pools naturally collect from the air in sulfur or carbon compounds. Acidic liking bacteria tend to stink bad to us humans, there often the subset of groups that are the results of food decay, hence its a basic instinct thing. Alkaline living bacteria don't tend to smell to us humans in the same way which is a good thing as were kinda covered in them.

Adding a biocide that releases something toxic as it breaks down is a sure way to kill you not the smell for long too.

DDoug · Jan 10, 2019

CarbideBob said:
For some reason I place my trust in coolant sales people below that of tool salesmen.
That is a very low bar.
Bob

The machine shop ran the test's and I saw the spreadsheet that they, themselves
created. All tool life info was generated by them, no coolant salesperson involved.
The only thing the coolant vendor did was test the water beforehand, and suggest
the switch to DI.

DI water / Filtration / Water Softener for coolant water?

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