Rodi water vs tap

Oiler3535 · 08/29/2019, 12:20 PM

Been in the hobby 2 years now. 1 unexplained mini crash but nothing major. I finally stopped using treated tap water and bought an rodi unit. Just a cheap RO Buddie but figured would be decent. I haven't noticed any differences in my tank, but I bought a tds unit for curiosity. My tap water is between 65 and 70. After the 3 stages of RO, it's 1. After the DI it's zero. I know the 0 is expected. Is the 70 out of the tap and 1 after RO about normal? How high should I allow the other 2 numbers get before replacing media?

hkgar · 08/29/2019, 02:00 PM

The expected rejection rate after RO is generally between 95% and 99%, so would be very good.. Tap after of 70 is very good. IMHO. Mine is 280, but is well water and also after the softener.
Your carbon and sediment filters should be changed every 3-6 months, depending on usage. RO membrane should last 5+ years.

Oiler3535 · 08/29/2019, 03:35 PM

Quote:

Originally Posted by hkgar

The expected rejection rate after RO is generally between 95% and 99%, so would be very good.. Tap after of 70 is very good. IMHO. Mine is 280, but is well water and also after the softener.
Your carbon and sediment filters should be changed every 3-6 months, depending on usage. RO membrane should last 5+ years.

Well, there's no way this DI cartridge is lasting that long. The bottom inch is already turning colour and has only done maybe 30g of water.

As for the others, what ppm would you wait for the output to be before changing. I don't do regular water changes so a calendar isn't going to work. It's 1 now, wait until above 5? 10? 2?

mcgyvr · 08/29/2019, 04:24 PM

Prefilters would be changed based on pressure loss not tds..
Ro membrane is changed when the rejection ratio falls outside a predetermined lower limit..
90% is decent number..

Di stage is often replaced when tds is 2-5 on average...but typically at the same time as the prefilters

Oiler3535 · 08/29/2019, 04:40 PM

Quote:

Originally Posted by mcgyvr

Prefilters would be changed based on pressure loss not tds..
Ro membrane is changed when the rejection ratio falls outside a predetermined lower limit..
90% is decent number..

Di stage is often replaced when tds is 2-5 on average...but typically at the same time as the prefilters

Thanks. Rejection rate not measurable for me. I just send it down the shower drain.

mcgyvr · 08/29/2019, 05:15 PM

Rejection is a comparison between input tds and tds at output of membrane...measuring waste is not necessary

Oiler3535 · 08/29/2019, 10:13 PM

Quote:

Originally Posted by mcgyvr

Rejection is a comparison between input tds and tds at output of membrane...measuring waste is not necessary

Thanks. The line between feeling stupid and learning can be invisible at times

hkgar · 08/30/2019, 07:39 AM

If your tap water tds is 70 and post ro tds is 1 than rejection rate is 98.5%, which is very good.

I change pre filters when pressure starts to drop and di when tds post di is 1.

FamilyTank · 09/01/2019, 03:41 PM

Quote:

Originally Posted by Oiler3535

Thanks. The line between feeling stupid and learning can be invisible at times

Lol, I love it! 😁 We've all been there at some point in life's travels.

rocsec1 · 09/06/2019, 06:43 PM

And many people dance back and forth over the line

Timmayyy · 09/13/2019, 04:01 PM

The only time I tried tap water, I got a nasty algae bloom. It must have bee the high silicates.

08/29/2019, 12:20 PM	#1
Oiler3535 Registered Member Join Date: Oct 2016 Location: Ottawa Valley, Canada Posts: 90	Rodi water vs tap Been in the hobby 2 years now. 1 unexplained mini crash but nothing major. I finally stopped using treated tap water and bought an rodi unit. Just a cheap RO Buddie but figured would be decent. I haven't noticed any differences in my tank, but I bought a tds unit for curiosity. My tap water is between 65 and 70. After the 3 stages of RO, it's 1. After the DI it's zero. I know the 0 is expected. Is the 70 out of the tap and 1 after RO about normal? How high should I allow the other 2 numbers get before replacing media?

08/29/2019, 02:00 PM	#2
hkgar Registered Member Join Date: Oct 2002 Location: Dewitt MI Posts: 5,051	The expected rejection rate after RO is generally between 95% and 99%, so would be very good.. Tap after of 70 is very good. IMHO. Mine is 280, but is well water and also after the softener. Your carbon and sediment filters should be changed every 3-6 months, depending on usage. RO membrane should last 5+ years. __________________ Gary 180 gallon, 40 gallon sump, 3 250 W MH + 4 80W ATI T5's, MTC MVX 36 Skimmer, Apex controller Aquamaxx T-3 CaRx Current Tank Info: A 2 Barred Rabbitfish, Red Head Salon, Yellow/Purple, McMaster Fairy, Possum, 2 Leopard Wrasses, Kole, & Atlantic Blue Tangs, 2 Percula Clown, 3 PJ and 1 Banggai Cardinalfish , Swallowtail, Bellus and Coral Beauty Angels

08/29/2019, 04:24 PM	#4
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	Prefilters would be changed based on pressure loss not tds.. Ro membrane is changed when the rejection ratio falls outside a predetermined lower limit.. 90% is decent number.. Di stage is often replaced when tds is 2-5 on average...but typically at the same time as the prefilters __________________ Who me?

08/29/2019, 05:15 PM	#6
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	Rejection is a comparison between input tds and tds at output of membrane...measuring waste is not necessary __________________ Who me?

08/30/2019, 07:39 AM	#8
hkgar Registered Member Join Date: Oct 2002 Location: Dewitt MI Posts: 5,051	If your tap water tds is 70 and post ro tds is 1 than rejection rate is 98.5%, which is very good. I change pre filters when pressure starts to drop and di when tds post di is 1. __________________ Gary 180 gallon, 40 gallon sump, 3 250 W MH + 4 80W ATI T5's, MTC MVX 36 Skimmer, Apex controller Aquamaxx T-3 CaRx Current Tank Info: A 2 Barred Rabbitfish, Red Head Salon, Yellow/Purple, McMaster Fairy, Possum, 2 Leopard Wrasses, Kole, & Atlantic Blue Tangs, 2 Percula Clown, 3 PJ and 1 Banggai Cardinalfish , Swallowtail, Bellus and Coral Beauty Angels

09/06/2019, 06:43 PM	#10
rocsec1 Registered Member Join Date: Jul 2012 Location: Medina oh Posts: 1,782	And many people dance back and forth over the line

09/13/2019, 04:01 PM	#11
Timmayyy Registered Member Join Date: Sep 2019 Posts: 82	The only time I tried tap water, I got a nasty algae bloom. It must have bee the high silicates.