Some people do use their water softener for evaporation refill. It takes a pretty good sized unit and requires a lot of recharging if you have to refill regularly.
Nanofiltration of my fill water. What is up with that?
- Thread starter It's pooler in AZ
- Start date
A water softener will work, many people use water softeners. However, a typical home water softener is not designed to handle the amount of water used when filling a pool all at once. You can use a water softener to fill a pool, but expect it to take extra time, and you will need to be around to add salt/regenerate several times during the fill. Water softeners generally work just fine for topping off to compensate for evaporation, as the amount of water used at one time for topping off is normally in the range they are designed to handle.
I agree that would be cumbersome for a mass refill of a pool. But for the OP's need of 70 gallons a day a small to medium sized home water softener should be fine and not need an abnormal rate of salt refills...
Bruce, by poor recovery do you mean when you factor in the brine wash/ backflush of the softener? How much waters typically used in a home softener to clean it? I had one in our last house but I never paid attention to how much water was used for the backwash...I think we got about 850 gallons with our hardness of about 20 before it would "regenerate"...80 gallons would be an 8.6% loss rate (on the total of 930) so unless a regen cycle took more than 160 gallons then the rate would still be better than an RO treatment water efficiency wise...how much salt is put back in the softened water?
Your RO treatement obviously does a lot more for the water than just calcium correction
Your RO treatement obviously does a lot more for the water than just calcium correction
Water loss in a water softener is significantly lower than for a home RO unit, though well above zero. A typical unit might lose say 75 gallons per cycle, which will work out to something around 10% depending on how far you are trying to reduce the CH level.
The amount of salt added depends on how much the CH level is lowered. The more you lower the CH level, the more salt that gets put into the water. Salt isn't as bad as CH because the amount of salt added is a lower percentage of the maximum salt level the pool can tolerate, compared to the CH % of the max CH level. Thus, you can generally go much longer with a water softener than without. In many cases you would never notice the salt accumulating because winter dilutions, when CH, and thus salt, levels are normally lower, take care of it easily. However, people with very high CH levels can end up accumulating too much salt in the pool and end up needing to use an RO treatment or replace massive amounts of water despite the water softener.
Some very small RO units feed the "waste" water back into the household water supply lines. This only works when the amount of water going through the RO unit is very small compared to the total water usage. This might be done in a system designed to feed a dedicated filtered water tap, but never in a unit of any size.
The amount of salt added depends on how much the CH level is lowered. The more you lower the CH level, the more salt that gets put into the water. Salt isn't as bad as CH because the amount of salt added is a lower percentage of the maximum salt level the pool can tolerate, compared to the CH % of the max CH level. Thus, you can generally go much longer with a water softener than without. In many cases you would never notice the salt accumulating because winter dilutions, when CH, and thus salt, levels are normally lower, take care of it easily. However, people with very high CH levels can end up accumulating too much salt in the pool and end up needing to use an RO treatment or replace massive amounts of water despite the water softener.
Some very small RO units feed the "waste" water back into the household water supply lines. This only works when the amount of water going through the RO unit is very small compared to the total water usage. This might be done in a system designed to feed a dedicated filtered water tap, but never in a unit of any size.
Yes, exactly. If your CH levels are high enough and your evaporation rate is high enough you have few practical choices, and essentially must ether replace most of the water each year or get an RO treatment each year. In somewhat less drastic situations there are more choices. My favorite mid-range CH issue setup is to use a combination of softened water, straight fill water, and partial winter water replacement. There are also many other combinations of CH mitigation that work in that situation. In milder conditions, you have even more choices, and can go with a water softener alone, small annual partial water replacements, an RO treatment every couple of years, or various combinations.carlscan26 said:
Maybe someday a solution like what It's pooler in AZ was attempting will also be possible. The technology isn't really there yet, but there is no fundamental reason why it can't work. Hopefully there will eventually be some kind of nano-filtration or RO system that is high enough efficiency and affordable.
- Nov 4, 2010
- 33
This answer is for simicrintz
The RO is hooked up to both the hot and cold lines. The waste is pumped back into the hot water line and used. I was looking for something to hook up to my fill line and RO the fill water so it would not be a closed loop system. I am not sure about your other questions but this might work in the right spa or small pool.
I do not want to add the salt to the pool a regular softener would add.
The RO is hooked up to both the hot and cold lines. The waste is pumped back into the hot water line and used. I was looking for something to hook up to my fill line and RO the fill water so it would not be a closed loop system. I am not sure about your other questions but this might work in the right spa or small pool.
I do not want to add the salt to the pool a regular softener would add.
- Nov 4, 2010
- 33
- Nov 4, 2010
- 33
Thank you Jason, your wisdom precedes you. Now if I could just find a mad scientist who would work for free I think we could solve this with a million or two.JasonLion said:
The "problem" with R/O is that it needs high pressure and a waste location for the brine solution to be effective. The low pressure units just cannot come up with good recovery rates, which is what keeps them under counter for limited drinking water supply at this point. Additionally, R/O membranes do not like chlorine or scale, so steps need to be taken to avoid introducing that into the membranes as well. Until (if) this is ever solved, I don't really see this as an option for swimming pools.
I still don't understand how they think that is a zero waste system, or how they put the water back into the hot water. What if you are running cold water only; where does it go? How does the hot water store it? I don't want to hijack the thread with this kind of stuff, but it is a bit confusing to me!
I still don't understand how they think that is a zero waste system, or how they put the water back into the hot water. What if you are running cold water only; where does it go? How does the hot water store it? I don't want to hijack the thread with this kind of stuff, but it is a bit confusing to me!
The zero waste system removes the minerals from the special filtered water tap and forces the extra minerals into the hot water pipe. Essentially, your hot water taps have extra minerals compared to your cold water taps. The water in the hot water pipe is forced to flow backwards through the hot water pipe back towards the supply line while the filtered tap is running. Since the total amount of filtered water used is very small compared to the amount of water used in the house as a whole, there is never enough mineral enhanced water to actually make it back to before the water heater, so it never loops back into it's own input. Your hot water supply ends up being higher in minerals than your cold, but the special treated water faucet is treated.
If you never ever ran the hot water, the mineral enhanced water would eventually make it back to the cold water supply and the entire system would stop working. But that will never happen in a real household when the filtered water is only used for drinking and cooking through a special filtered tap and all the rest of the household water comes from untreated water. The system works specifically because it only processes a small portion of the total water flow, moving the minerals away from the filtered tap and towards the hot water tap. In effect the hot water tap is the waste water stream, but (used appropriately) the amount of mineral enhancement is low enough that no one notices.
If you never ever ran the hot water, the mineral enhanced water would eventually make it back to the cold water supply and the entire system would stop working. But that will never happen in a real household when the filtered water is only used for drinking and cooking through a special filtered tap and all the rest of the household water comes from untreated water. The system works specifically because it only processes a small portion of the total water flow, moving the minerals away from the filtered tap and towards the hot water tap. In effect the hot water tap is the waste water stream, but (used appropriately) the amount of mineral enhancement is low enough that no one notices.
Jason do you know what are the posible ranges of salt that get added to conditioned water?
It's pooler in AZ said:
Using chlorine we're already adding salt...I'm curious what Jason can tell us on my post just above this re: salt levels from a softener. I image they are relatively low? If they are high enough then perhaps it may be an interesting idea to switch to a SWG if you regularly use softened water to refill the pool? You'd get double use of the residual salt...
I tested a pool in the early part of last month where the Ch was about 200. The people told me that they have not changed their water in about 6 years. I next measured the TDS, and it was around 8,000. For giggles I checked salt, and that was over 6,000. I happened to ask them if they had a water softener, which they said they did. Turns out they had been using soft water to fill the pool for the last 6 years! They had no idea, but did say that they had often wondered where they were putting all the water that they were getting billed for each month!
Chem geek is much better at this kind of calculations than I am, but I'll give it a try. My rough estimate is that the water softener adds [corrected]12 ppm[/corrected] of salt for every 10 ppm of CH that it removes from the water. I've never done a workup for the ion exchange process going on in the water softener before so I might have that off somewhat, but even if I got something wrong that should still be in the right general range.
In areas where this is going to be a big issue, the water softener might be removing 200 or 300 ppm of CH, which means something like [corrected]240 or 360 ppm[/corrected] of salt added. Over time the salt will accumulate, but since you are [corrected]adding about the same amount of salt as CH[/corrected] and salt can go way higher than CH can before it causes problems, you can go much longer before doing something drastic.
In areas where this is going to be a big issue, the water softener might be removing 200 or 300 ppm of CH, which means something like [corrected]240 or 360 ppm[/corrected] of salt added. Over time the salt will accumulate, but since you are [corrected]adding about the same amount of salt as CH[/corrected] and salt can go way higher than CH can before it causes problems, you can go much longer before doing something drastic.
There's two sodium ions released for every calcium ion that is exchanged because calcium has twice the charge of sodium. CH is in units of calcium carbonate while TDS or salt levels are measured in units of sodium chloride. So every 10 ppm CH is (2 sodium/calcium)*(58.443 g/mole sodium chloride) * (10 ppm calcium carbonate)/(100.0869 g/mole calcium carbonate) = 11.7 ppm salt. It looks like you forgot the factor of 2 due to the charge difference.
Still, your point about this being a slow buildup process is still valid.
Still, your point about this being a slow buildup process is still valid.
BTW, I declined to treat their pool since I didn't feel that with the low CH and allowing for dilution of the salt going into winter rains (what little we get!) that they were in any real danger. They appreciated the fact that I didn't try and convince them they needed me at that time. They have since been checking their water and topping off with water outside the softener, with good results and no damage.