First five minutes of RO/DI...trash it?

DUPioneers · 12/01/2012, 11:29 PM

So. Possibly strange question, here...

The first 5 minutes of water that comes out of an RO/DI system is, relatively speaking anyway, "high" in TDS.

Do you guys bother trashing this water?

If so, how does that work with a float switch controlled storage reservoir?

From a practical perspective, I am not enamored of being in a position where I have to babysit my RO/DI system and "turn it on when I need water". I just want it to work with the float switch and turn on when my storage reservoir needs water...then turn off when it doesn't. Also, I don't want to dick around with solenoids, timers, or anything of that sort. Am I dreaming?

Ron Reefman · 12/02/2012, 05:40 AM

How bad is the TDS of the first 5 minutes? And what is the TDS after that? My personal opinion is (and many here will disagree) that 5 minutes of water with a TDS of say 30 and the balance of 'normal' low TDS is nothing to get worked up about if you are filling a 35g Brute or a holding tank of 25g or more. If you are using an auto top off and are regularly pulling small amounts of water out and wherefore running the RO/DI for short periods of time, I'd find a new way to control making water. I have a 45g tank and I try to use most of it before I turn the RO/DI on and fill it.

IMHO reefers freak out about TDS numbers way too much. I didn't run any DI for my first few years and used water with 30-40 TDS all the time and never had an issue. A friend of mine uses well water with a TDS just over 100 and he keep lps and some sps with no issues.

Denbf58 · 12/02/2012, 06:21 AM

what i did was cut the line before my di/unit put in a T and a shut off valve that way when i turn on the water to the ro unit and open the valve and let it dump down the drain for 5 min. i also use this line to fill drinking water jugs

downbeach · 12/02/2012, 06:48 AM

What do you mean by "high"? Where are your seeing the TDS, i.e. after the membrane or after the DI unit? My TDS after my membrane are around 10, when I first turn it on, and in about 10 seconds are down to 1. But the output of the DI is always at '0'.

sasharotty · 12/02/2012, 08:35 AM

Quote:

Originally Posted by Ron Reefman

How bad is the TDS of the first 5 minutes? And what is the TDS after that? My personal opinion is (and many here will disagree) that 5 minutes of water with a TDS of say 30 and the balance of 'normal' low TDS is nothing to get worked up about if you are filling a 35g Brute or a holding tank of 25g or more. If you are using an auto top off and are regularly pulling small amounts of water out and wherefore running the RO/DI for short periods of time, I'd find a new way to control making water. I have a 45g tank and I try to use most of it before I turn the RO/DI on and fill it.

IMHO reefers freak out about TDS numbers way too much. I didn't run any DI for my first few years and used water with 30-40 TDS all the time and never had an issue. A friend of mine uses well water with a TDS just over 100 and he keep lps and some sps with no issues.

100 ppm that's a little risky no?? What if out of that 100 or 40 in your case is copper. There goes your reef. I think reefers freak out because they have way to much invested to lose there reef for some 30 dollar filters.

mfinn · 12/02/2012, 10:09 AM

Quote:

Originally Posted by DUPioneers

So. Possibly strange question, here...

The first 5 minutes of water that comes out of an RO/DI system is, relatively speaking anyway, "high" in TDS.

Do you guys bother trashing this water?

I must be missing something.
No matter what time has passed the end water coming out of a RO/DI filter should be 0 TDS. If it isn't, then it's time to replace the filters.

Now, the TDS coming out of the RO side may have a TDS reading of 1 or more and that's normal, but it still has to go through the DI side.

bnumair · 12/02/2012, 11:23 AM

i dont dump any ro/di water when it first comes on. i have a 50gal drum that fills up with ro/di water. its controlled by genesis renew/revoc system.
when water in bin reaches at last 2 inch level sensor detects low water and turns the ro/di unit on and fills the 50gal drum till the high sensor is triggered.
So in reality i am not making small batches. Its making almost 45-48 gal at a time thus reducing the tds factor to 0.

Palting · 12/02/2012, 01:02 PM

Quote:

Originally Posted by DUPioneers

So. Possibly strange question, here...

The first 5 minutes of water that comes out of an RO/DI system is, relatively speaking anyway, "high" in TDS.

Do you guys bother trashing this water?

If so, how does that work with a float switch controlled storage reservoir?

From a practical perspective, I am not enamored of being in a position where I have to babysit my RO/DI system and "turn it on when I need water". I just want it to work with the float switch and turn on when my storage reservoir needs water...then turn off when it doesn't. Also, I don't want to dick around with solenoids, timers, or anything of that sort. Am I dreaming?

I go with Ron. Between my 2 tank systems and their ATO reservoirs, I consume and fill up a 55 gallon Brute weekly, takes 8-10 hours to fill. So the first 5 minutes is literally a drop in the bucket, not worth worrying about. Been doing it for 3 years now, with no issues.

Quote:

Originally Posted by mfinn

I must be missing something.
No matter what time has passed the end water coming out of a RO/DI filter should be 0 TDS. If it isn't, then it's time to replace the filters.

Now, the TDS coming out of the RO side may have a TDS reading of 1 or more and that's normal, but it still has to go through the DI side.

The first several minutes generally have a higher TDS. It doesn't mean you have to change the filters. It's from the water that has been sitting in the filters and membrane chamber stagnant for days since the last RODI run. The TDS before the DI on mine starts from around 60, then rapidly goes down like the meter at the gas pump to 0-1 within 30 seconds or so. The TDS after the DI starts maybe around 6-10, drops to zero even faster than the other one.

thegrun · 12/02/2012, 01:33 PM

Quote:

Originally Posted by Denbf58

what i did was cut the line before my di/unit put in a T and a shut off valve that way when i turn on the water to the ro unit and open the valve and let it dump down the drain for 5 min. i also use this line to fill drinking water jugs

This is what I do also. The first water passing the RO filter is high in TDS and these dissolved solids will not all be filtered out by the DI resin. Bypassing the initial water away from the DI filter will lengthen the life of your resin. This "high" in TDS water is none the less much purer than your tap water and make great drinking water.

on the spot · 12/02/2012, 01:42 PM

Short of baby sitting or monkeying around with solenoids and timers, yeah you are sort of stuck with using the high TDS water.

I choose the monkeying around route myself. Resin is expensive.

The cheap way is add two valves and two tees to your system and run it manually. the float valve still shuts off the water, you just need to close a valve when your container is full. When you need more water, open one valve to waste for a few minutes, close that valve and open the valve to the DI.

12/01/2012, 11:29 PM	#1
DUPioneers Registered Member Join Date: Nov 2010 Location: Denver, Colorado Posts: 142	First five minutes of RO/DI...trash it? So. Possibly strange question, here... The first 5 minutes of water that comes out of an RO/DI system is, relatively speaking anyway, "high" in TDS. Do you guys bother trashing this water? If so, how does that work with a float switch controlled storage reservoir? From a practical perspective, I am not enamored of being in a position where I have to babysit my RO/DI system and "turn it on when I need water". I just want it to work with the float switch and turn on when my storage reservoir needs water...then turn off when it doesn't. Also, I don't want to dick around with solenoids, timers, or anything of that sort. Am I dreaming? __________________ 180 gal build in the works.........

12/02/2012, 05:40 AM	#2
Ron Reefman Registered Member Join Date: Jul 2009 Location: Cape Coral, FL Posts: 10,431	How bad is the TDS of the first 5 minutes? And what is the TDS after that? My personal opinion is (and many here will disagree) that 5 minutes of water with a TDS of say 30 and the balance of 'normal' low TDS is nothing to get worked up about if you are filling a 35g Brute or a holding tank of 25g or more. If you are using an auto top off and are regularly pulling small amounts of water out and wherefore running the RO/DI for short periods of time, I'd find a new way to control making water. I have a 45g tank and I try to use most of it before I turn the RO/DI on and fill it. IMHO reefers freak out about TDS numbers way too much. I didn't run any DI for my first few years and used water with 30-40 TDS all the time and never had an issue. A friend of mine uses well water with a TDS just over 100 and he keep lps and some sps with no issues. __________________ The good thing about science is that it's true whether or not you believe in it. (Neil deGrasse Tyson) Visit my build thread http://www.reefcentral.com/forums/showthread.php?t=2593017

12/02/2012, 06:21 AM	#3
Denbf58 Registered Member Join Date: Mar 2008 Location: selden N.Y. Posts: 885	what i did was cut the line before my di/unit put in a T and a shut off valve that way when i turn on the water to the ro unit and open the valve and let it dump down the drain for 5 min. i also use this line to fill drinking water jugs __________________ Life is good Current Tank Info: 75gal reef ready koralia 3, 30g sump, 4b 48" t5s lighting, 29g reef with breeding pair clowns 55g reef 55g freshwater

12/02/2012, 11:23 AM	#7
bnumair Dr. Reef at ur service Join Date: May 2009 Location: Tulsa, Ok, USA Posts: 7,751 Blog Entries: 15	i dont dump any ro/di water when it first comes on. i have a 50gal drum that fills up with ro/di water. its controlled by genesis renew/revoc system. when water in bin reaches at last 2 inch level sensor detects low water and turns the ro/di unit on and fills the 50gal drum till the high sensor is triggered. So in reality i am not making small batches. Its making almost 45-48 gal at a time thus reducing the tds factor to 0. __________________ Water Quality: NO3 0,Phos 0,Cal 440,Alk 7.5,Mag 1300 "Reef Fast, You Crash, Reef Slow, You Pass" Mike's Reef 3:16 Current Tank Info: 350g DT,95g sump, 50g Frag tank, 4800gph return 4x Sea swirls. 6x AI Vega Color. 200# Pukani rock, dual recirculating skimmer, Biopellet, GFO Carbon rx's, Cal rx. Closed loop. 1.5hp chiller, genesis renew. Apex & RKE

12/02/2012, 06:48 AM	#4
downbeach Registered Member Join Date: Nov 2006 Location: Smyrna, Delaware Posts: 3,767	What do you mean by "high"? Where are your seeing the TDS, i.e. after the membrane or after the DI unit? My TDS after my membrane are around 10, when I first turn it on, and in about 10 seconds are down to 1. But the output of the DI is always at '0'.

12/02/2012, 01:42 PM	#10
on the spot Registered Member Join Date: Oct 2007 Location: West Michigan Posts: 1,010	Short of baby sitting or monkeying around with solenoids and timers, yeah you are sort of stuck with using the high TDS water. I choose the monkeying around route myself. Resin is expensive. The cheap way is add two valves and two tees to your system and run it manually. the float valve still shuts off the water, you just need to close a valve when your container is full. When you need more water, open one valve to waste for a few minutes, close that valve and open the valve to the DI.