System capacity is rated for total nitrate capacity only. Allotment of up to 50% of total nitrate capacity
may be consumed by other ions in the raw water. Before installing a nitrate system, SWT recommends a water analysis
and factory consultation for proper equipment sizing and regeneration settings.
MORE ON NITRATE REMOVAL
The science of nitrate removal is simple, but for obvious reasons, cannot be taken lightly. The two most often used technologies
for nitrate reduction are Reverse Osmosis (RO) and Ion Exchange. Ion Exchange is a more recent technology. RO is much more
costly per gallon of treated water, except for third faucet drinking water applications. RO is a more full-proof method with
less maintenance responsibility to the homeowner, but impractical in whole house applications.
Up until recently, nitrate was an ion that once pulled from the water with a resin bed, had a very loose hold on the resin bead
and a competitive ion, such as sulfate, could come along and push an already held nitrate ion back into the water. It has only
been recently that this problem has been overcome.
ProSelect Nitrate Resin is one of the first of its kind
of resin that will not allow a competing ion to displace a captive nitrate ion back into the water supply. However, the selective
advantage of the resin bead to the nitrate is still minimal. This means it almost acts as a first come, first served competition
with a slight preference going to the nitrate. Other ions in the raw water will not displace the nitrate back into the water stream,
but nitrates will not always displace sulfates either. That is why in all nitrate applications, a water analysis should be done to
insure the amount of nitrate in the water, and you also need to know if there are sulfates present which will compete for room in
the resin bed. Then size the system accordingly.
It is very easy to do. It only requires a little math. If for example you have 30 PPM of nitrate, and 10 PPM of sulfate, that
means you have a total of 40 PPM fighting for room in the bed. 25% is sulfate, and 75% is nitrate. That means that in a 1 cubic
foot nitrate system with a capacity of 67,000 PPM/10 lb. of salt regenerant, the bed will be completely exhausted after 16,750 PPM
of sulfate and 50,250 PPM of nitrate. So your total nitrate capacity would be 50,250 PPM nitrate (75% of 67,000 PPM) or 1,675 gallons
of water. (50,250 PPM of room divided by 30 PPM/gallon of water equals 1,675 gallons before the bed is full.)
(Total bed capacity) – (% of sulfate to nitrate) = (Total nitrate capacity)
Still, some dealers like to reduce that number to err on the safe side. They may leave a 20% buffer to allow for an excess of water use.
|OTHER THINGS TO REMEMBER
||A nitrate system should always follow an iron filter or a water softener in any multi-tank treatment system.
||Iron will foul out a nitrate resin faster than a cation resin.
||Both a water softener and a nitrate removal system use salt (sodium chloride) to regenerate. However, the nitrate
resin is using the chloride side of the salt for regeneration, as opposed to a water softener which uses the sodium side.
||Potassium chloride can be used, but remember, potassium chloride on average has 20% less chloride per pound than
salt. Control settings have to be adjusted accordingly.