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Thread: Water Spots

  1. #1
    Daryl is offline Junior Member
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    Question Water Spots

    Hello I have a portable water softener system to wash my cars. it is a WET SPOT softwater washdown system. It has a ametek big blue pre filter but it still leaves spots on the cars. water tests soft so I am thinking I need a different element in the filter housing . What would you suggest to replace it with drinking quality is not an issue as I just use the system to wash cars. Thanks in advance Daryl

  2. #2
    Roxanne is offline Senior Member
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    Default West Spots

    Quote Originally Posted by Daryl
    Hello I have a portable water softener system to wash my cars. it is a WET SPOT softwater washdown system. It has a ametek big blue pre filter but it still leaves spots on the cars. water tests soft so I am thinking I need a different element in the filter housing . What would you suggest to replace it with drinking quality is not an issue as I just use the system to wash cars. Thanks in advance Daryl

    Hi Daryl,

    What micron rating is the filter you are currently using? My first suggestion would be to use a filter with a small micron rating.
    Roxanne Crawford
    FiltersFast
    www.filtersfast.com
    866-438-3458

  3. #3
    Daryl is offline Junior Member
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    Question Pentek

    I am using a Pentek DGD-5005 50 micron pre 5 micron post Daryl

  4. #4
    rscardigno is offline Administrator
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    Smile DGD-2501 25 micron pre, 1 micron post

    You can try the DGD-2501 to see if going down to 1 micron makes a difference. They can be found at http://www.filtersfast.com/Pentek-DG...rad-Filter.asp.

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    Daryl is offline Junior Member
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    Thumbs up tHANKS

    Thanks ordered it ! Daryl

  6. #6
    Andy CWS is offline Moderator
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    A water softener does not assure you of spot-free water. That is usually provided by some kind of membrane system as used at car washes.

    A prefilter will probably also have no effect on spotting. Your softener exchanges hardness elements for softened elements; typically calcium carbonte for sodium. The sodium will leave some spots on your car's finish but should be able to wipe them off with a moisteded towel.

    Hardness mineral spot will dry hard and need to be 'scraped' off.If you want a spot-free rinse, keep a couple of gallons of RO water and use it for a final rinse.

    Andy

  7. #7
    Daryl is offline Junior Member
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    Andy what is ro water? thanks Daryl

  8. #8
    Andy CWS is offline Moderator
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    RO water, sorry, is reverse osmosis water. RO removes virually all total dissovled solids (TDS) including sodium. Quality car washes use these for the final rinse and the water usually comes out in smaller amounts.

    Residential use is at the sink with a dedicated faucet and maybe connected to the fridge to make ice cubes clearer.

    Andy

  9. #9
    Daryl is offline Junior Member
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    Default ro system

    Is there a ro system available that is portable for washing cars? thanks for your time Daryl

  10. #10
    Andy CWS is offline Moderator
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    As for an "portable RO" designed for washing cars, generally not. However, I did see one on eBay recently. It comes with a movable cart and all. You could build one but the cost may be too high to justify.

    Sodium is water friendly and it can be wiped off with a little elbow grease.

    Andy

  11. #11
    Andy CWS is offline Moderator
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    I checked again on eBay and it is still there auction as a "window cleaning".

    Andy

    ps. I hope this isn't breaking any forum rules. Sorry if so.

  12. #12
    a1certified is offline Junior Member
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    I'm trying to come up with a rational system as well with the same end-point. Looking for spot free car washes.

    There are two common commercial products that I've heard of. One is called Mr. Clean Autodry and it is a spray handle type device that has changeable filters built into it. The device costs about $40 and each filter is supposed to last for 3-4 washes. Each replacement filter is about $6-7. I've heard mixed reviews on this one.

    There is another higher-end type product called CR Spotless that has 2 capacity models at $300 for the lower capacity model and $400 for the higher capacity model. Said to provide 100 gallons of spot free water for the lower capacity model and 300 gallons for the higher capacity model. Resin refills are about $45 for the lower capacity model and $90 for the higher capacity model. It appears to use 2 10" or 20" big blue housings, each filled with mixed bed deionizing resin. Also has a TDS meter attached to monitor output water cleanliness.

    My thoughts on this are that deionizing resin is expensive and not rechargeable (easily at home, at least) unless you have some strong acids and bases. I wonder if one would be better served by adding a particulate pre-filter of some sort to the system which hopefully would greatly increase the deionizing capacity of the system. In a high-flow system application such as car washing, a reverse osmosis system is impractical. But I assume that some sort of particulate pre-filter can be used get out a lot of junk at a fairly high flow rate.

    My question relates to what type(s) of filters one would recommend. There are several types available. I would like to know how they compare in filtration efficiency and flow rates possible at ordinary household water pressure (50-60psi). I have seen wound-string, cellulose, polypropylene, and paper type filters.

    After particulate filtration, would adding a carbon filter give any incremental benefit before going to deionization? Apparently carbon will absorb many substances that are of benefit in drinking water (with the exception of fluoride, nitrates and sodium), but do fluorides and nitrates cause water spots? Sodium will be filtered out by the deionizing resin. To expound on the original question, I don't think soft water is necessarily less "spotting" than hard water, but as mentioned, the spots are probably easier to remove than hard water spots caused by ions such as calcium. What you really want is not a water softener, but a water deionizer. As an aside, does anyone know what range of TDS readings one would get from a system that had a good particulate filter and good working water softener? Sodium (exchanged for calcium and other "hard" ions) will still make a reading on the TDS meter, won't it?

    My final step would be to run the water through a mixed-bed deionizing resin which would hopefully have a much easier time removing the few (?) remaining ions in the water.

    Does this sound like a reasonable analysis of the problem and proposed solution? Or am I missing something? I'm just starting my exploration of these topics and am by no means an expert. I'm just trying to understand the most reasonable approach one would take if the net result desired is deionized water for a spot-free car wash and one didn't have any concerns about suitability for drinking.

    Thanks for your thoughts.

    David

  13. #13
    Andy CWS is offline Moderator
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    Yes, you can get spot-free water with those refillable housings.

    Your cost is out of the question, in my opinion. What you make up for in initial cost are over taken by replacement and maintenance charges in a very short time, especially for a commercial application. $90 for every 400 gallons!? Whew.

    There are reasonably priced commercial ROs that can perform adequate service, are easy to maintain and costs will be justified. DI systems are mostly used in high tech manufacturing and medical grade applications. Washing cars...Uhm?

    Why would you want carbon? Odors? Organics? Not normally a problem for car washing. Another high maintenance product.

    Prefilters can must be determined by flow rate and may be put in a succession of larger micron down to smaller micron. It all depends on your water quality test results.

    If you DO use a DI system, you would want it to follow a prefilter, a softener and then an RO. If not, the DI resins will burn up faster a ZigZag at a Grateful Dead concert.

    Andy

  14. #14
    a1certified is offline Junior Member
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    That is exactly my thoughts with the replaceable cartridge systems. Low up front costs, followed by disposables that would bankrupt you.

    With respect to a system that can be used in a high-ish flow system (i.e. car washing) where you really want a stream of water to wash off particles and detergents, for example, and the end "filter" is a deionizing resin, do you really need a RO before that? My impressions from the RO system I have for my drinking water in the kitchen is that the production of RO water is slow and relies on a storage tank that gets depleted when the RO tap is opened and then slowly refilled by the RO system over time. This is not practical when you want a bunch of water - "right now".

    I was thinking of a carbon block filter prior to the DI component solely as a particulate filter (how many micron-equivalent would one consider a carbon block filter element to provide) and to filter out some of the ions that would otherwise bugger up the the DI resin; sort of a poor man's RO system when higher flow is required? Is there any merit to that line of thinking?

    Prior to the carbon block, I was planning on having some sort of X-micron particulate filter. What level of filtration would be optimal to minimize wear and tear on the DI resin? I've seen particulate filters from 30 microns down to 1 micron. Will even a 1 micron filter have any discernible DI resin-sparing effect? Does one get any reasonable amount of water flow through a 1 micron particulate filter?

    With this type of system, I would have a 2-canister Big Blue (10" or 20"?) system housing the particulate filter and the carbon block filter and then have a homebrew DI-resin filled "wand" that gives the final cleansing of the water before going out the house onto the cars.

    Particulate filters are cheap. Carbon block filters intermediate in price. And DI resin the most expensive component to replace.

    Thanks.

  15. #15
    a1certified is offline Junior Member
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    P.S. I guess I have a related question. The source water that I have can either be straight city water that is hard (12 grains?) or softened water that has gone through my whole house filtration system composed of a carbon filter and a Culligan water softener. Is the softened water (which I guess is relatively high in Na and Cl ions) any less demanding on the DI resin that the "hard" city water?

    Thanks.

  16. #16
    Andy CWS is offline Moderator
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    All your questions are reasonable and your goals are fairly clear to me. Naturally, any RO for commercial basis must follow at least two criteria: membranes large enough with ample pressure and feed to produce adequate supplier or retention tanks large enough to provide demand water when needed...or a combination of both.

    Retention for many car washes may be about 300-500 gallons at low pressure spray, with an RO that produces 1000 - 3000 gpd.

    Remember that a DI resin removes both cation and anions in either a mixed bed application or separate tanks each removing anions and cations. The lower the ion count you have going into the resins beds, the longer they will last, and the cheaper they will be to maintain. An RO is very effective at removing ionized particles such as sodium, thus saving the DI resin as a “final” polishing of the water.

    The RO should be preceded by a softener to convert calcium ions to sodium ions as membranes hate calcium but love sodium.

    You should not use a carbon filter as a particulate filter. It will naturally, have some effect at removing particles of a given size, but that is not where their excellence lies. As for pre-filters, use as big as possible to improve flow rate and longevity.

    If chlorine is to be removed then an up-flow carbon media tank would be recommended. The size, again, would be determined by the volume of water x the PPMs of Cl.

    Of course, a one micron filter may serve to improve the shelf-life of DI resins but only in that the resins will not accumulate foreign matter as in a softener. But remember, those resins don’t regenerate (at your location) and are simply replaced, so the purpose of a filter that fine becomes a moot point.

    I will go back to my previous statement that for spot free rinse at a commercial car wash, a properly sized RO will serve best. DI resins will be a pain and costs associated with on-going production will be regretful.

    Andy Christensen, CWS

  17. #17
    a1certified is offline Junior Member
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    Would creating the properly sized RO system result in the ability to rinse the car, let it air dry, and not have any spots? My impression is that the spots are caused by calcium and other minerals in water that get left behind as the water evaporates.

    Softened water is high in Sodium and Chloride, correct? Won't these leave spots behind as the water evaporates?

  18. #18
    Andy CWS is offline Moderator
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    Generally speaking, yes. The RO water will be virtually void of spotting elements such as calcium and sodium. Nothing will be perfect so levels of acceptability need to be set.

    The key difference between calcium and sodium spots is solubility. When water evaporates containing calcium (and other hardness salt/minerals/metals), the spots left behind cannot simply be removed by wiping with a moist towel, for example. The have 'calcified' and need to be removed by scaping or an acidic solution; both time consuming and adds expense.

    Sodium spots are water soluable and a moistened towel or RO water can easily remopve them to a satisfactory degree. Softened water normally contains sodium but generally separates chlorides from the salt. So it should be sodium that you are seeing. A poorly operating softener CAN produce salty results.

    Hope this helped a bit.

    Andy Christensen, CWS

  19. #19
    a1certified is offline Junior Member
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    Thanks for the clarification.

    What would be your recommendation for a cost effective larger-scale solution with higher flow-through rates?

    David

  20. #20
    Andy CWS is offline Moderator
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    There are numerous parameters to determine commecial RO usage. Source water conditions, pretreatment equipment, water and ambient temperatures, replacement parts' availability, maintenance schedules, etc., all help determine what makes it a lucrative business or hole that you pour water into.

    Rule of thumb dictates that the RO product rate should be twice the expentant actual use. Storage should correspond with adequate supply and recovery. Space can be a problem for storage.

    Most commecial ROs have multiple membranes that are 4" in diameter with pressure pumps and TDS meters for both product and concentrate waters.

    There are calculations for car washes based on the number of vehicle per hour that would be using the spot-free rinse cycles, but I don't have them off hand.

    If you visit a couple of local car washes, ask to inspect the water treatment systems and ask questions to the managers or owners. Most, I have found, are quite Ok with showing their equipment. Ask what problems they have had and how well it works. Don't present yourself as a 'competition' in thier area but more as a very interested customer and water enthusiast.

    You may find some very different approaches.

    Andy Christensen, CWS

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