the only "machines" that can remove nitrates would be either anerobic dinirifiers which are not machines but rather bioligical filters and are not applicapble to pools and ion exchagne units, once again, not a mahcine but considered a filter and also not applicable to pools. Reverse Osmosis is likewise considered a filter. I am not sure what you mean by
'machine'. Like I said the only practical way to lower nitrates in a pool is by dilution.
so are you saying that there are other ways to remove nitrates from the water other than dilution?? The point of being practical or not does not matter here. Some people have plenty of money to spend and would possibly by this filter to filter the nitrates. Most people don't think storing jugs and jugs of bleach and dumping them in the pool every day is practical eithher but some people still do it don't they?? We can't all afford a chlorine generator but some of us can and buy them and some of us would buy a denitrification filter as well.
Since you have hijacked this thread I will try and answer you. The point of being a practical solution to a problem very much matters!
As far as biological denitrifiers they won't work in a pool because:
1. they require a very slow flow or stagnent water (the process is done by anerobic bacteria)
2. chlorine would kill the denitrifying bacteria
3. it is an extremely slow process that would literally take weeks to months before the nitrates were significantly reduced
as far as reverse osmosis, it won't work in a pool because RO units have very slow flow rates and cannot process large volumes of water and there is much water that does not pass through that would be discarded as wastewater so you would lose a large percentage of the water even if you had a unit big enough to process your pool and would be refilling with other water anyway
It is also a slow process
as far as ion exchange,
the resin would get depleated and need regenerating rather quickly. since this type of resin is regenterated with a brine solution you would have that to deal with (which is also the reason it would not work with a salt pool, the salt water would just release any trapped nitrates from the resin back into the pool water)
The flow rate through the resin would need to be much slower than the flow rates in your average pool and the resin tank would need to be very large to accomodate the amount of water. The cost would be prohibitive.
this once again leaves dilution as the only PRACTICAL method to reduce nitrates in a pool.
Since you are hijacking this thread I will try and answer you again. It's not matter of how much it costs. These other ways just won't work on a pool because of the chlorine present and the high flow rate.
Anerobic denitrification is a very slow process and could take weeks or months to reduce the nitrates and the chlorine would kill the needed denitrifying bacteria in the filter.
reverse osmosis would take EVERYTHINK out of the water, not just the nitrates, and that is not desirable
Ion exchnage resins would need to be regenerated several times during the process and would not work at all in a salt pool because a brine solution is used for regeneration so in a salt pool the nitrates would just go right back in the water and not stay in the resin. The cost would be prohibitive for the equipment needed.
It IS a matter of what is practical. Impractical solutions are not solutions to problems at all.
Water replacement is the only viable way to reduce nitrates in a pool.
Phosphate removal aside, if an idea within a post is not practical, then it's impractical. I see no point in posting impractical ideas or solutions on TFP. If advice or ideas are not practical, they have no value to the members on TFP.