If an RODI unit is rated at so many gallons per day, does that mean in a 24 hour period?

[powers2001]

If I have a 100 GPD RO unit then gallons produce in an hour is 4.17? 100/24=4.17 . Then time to fill a 13 gallon reservoir would be 3.12 hours. 13 / 4.17 = 3.12 . Well this is kind of strange. An Apex DOS at full speed can do an automatic water change at the rate of 1.3 gallons per hour. I have a 13 gallon salt reservoir so it would take 10 hours to do a complete water change. 10 / 1.3 = 10 . That means the time it takes the DOS to empty the salt reservoir is 3 times longer than it takes the RODI to fill it. And I thought RODI’s were slow !!!!

 

[mrlavalamp]

Get a faster pump?

 

[Gtinnel]

Yes that is how it works, but that gpd rating is not accurate. There are many factors that can change how quick it produces water. Mine is 100 gpd and it actually produces closer to 150gpd.

 

[Pistondog]

Water pressure in and degree of filter clog will change gpd.

 

[powers2001]

Well the reason I did this exercise is I only have one water vessel for both top-off and salt water change. So I will fill and empty the vessel through out the month with RO water for top-off. Then once at the end of the month I’ll fill the vessel specifically do an approximately 15% water change that takes 10 hours. I wanted to know if a significantly amount of water evaporates during the water change before the vessel is empty and I start filling it again this time for top-off once more. Well after the first hour of refill I’ll have ~4 gallons. So 4 gallons will be way more than enough to replace the water that may have evaporated during the 10 plus 1 hours.