TDS meter before or after DI filter?
- Thread starter jwheeler
- Start date
You really want three meters.
1. Before the pre filters of the RO/DI unit. This shows the TDS of the supply water.
2. After the RO of the RO/DI unit. This tells you how the RO membrane is doing. Say you have a 90% rejection rate membrane and the supply water has 100 TDS. This would mean you should have about 10 TDS coming from the membrane. If it goes too far above that, there's a problem.
3. One after the DI. If it goes above 1, it's time to start checking the unit over. If the one before the DI hasn't changed, you need new DI resin.
A pressure gauge is good after the RO's pre filters. As the sediment filter plugs up, the pressure will decrease. This means it's time to replace both pre filters. Though, I change mine every six months.
1. Before the pre filters of the RO/DI unit. This shows the TDS of the supply water.
2. After the RO of the RO/DI unit. This tells you how the RO membrane is doing. Say you have a 90% rejection rate membrane and the supply water has 100 TDS. This would mean you should have about 10 TDS coming from the membrane. If it goes too far above that, there's a problem.
3. One after the DI. If it goes above 1, it's time to start checking the unit over. If the one before the DI hasn't changed, you need new DI resin.
A pressure gauge is good after the RO's pre filters. As the sediment filter plugs up, the pressure will decrease. This means it's time to replace both pre filters. Though, I change mine every six months.
