RO/DI TDS question

[MrDJeep123]

1) 5 gallon jug has 096ppm and the other has 001ppm. My guess is it took that long to flush the unit? I ran the unit for about 10 minutes, I thought. But the part I don't understand, is if it weren't flushed, would the clean water be so high? :confuse:

 

[redfishbluefish]

What was in the first jug before you started putting RO/DI water in it? Could it just be salt residue?

 

[MrDJeep123]

Possibly. Thinking about it, I did put some salt in it some time ago. Perhaps I should do a better job of rinsing them out.

Awesome screen name btw.

 

[AZDesertRat]

Something that helps is a DI bypass valve installed between the RO membrane and the DI filter so you can flush the initial TDS creep to waste. Its not a huge amount of water but it can and will greatly shorten your DI life. Open the valve each time you start making water and monitor the RO only TDS until it reaches its lowest point before letting it reach the DI and you flush the TDS creep water out so it does not prematurely exhaust your DI resin. It coud extend your DI quite a bit.

Make sure your containers are clean and used only for RO/DI or at least measure your RO/DI TDS straight from the unit an not the storage container so you know it is the container and not the filter. A dirty contaner which was used for a water change isn't the end of the world where contaminated water could be and you need to be able to distinguish between the two.

 

[MrDJeep123]

There is a bypass on the waste water for flush. I don't know anything about the DI bypass. I haven't given much thought about TDS until recently. I was wanting to compare our unit to what we get at Culligan refill for our drinking water.

I'm not concerned about the jugs getting mixed for anything else. I use only the 2 jugs for water changes/refills. I'm also not overly concerned with those numbers. As long as I'm getting better than our TAP and currently better than Culligan, that's all that concerns me.

 

[ReeferEric]

Something that helps is a DI bypass valve installed between the RO membrane and the DI filter so you can flush the initial TDS creep to waste. Its not a huge amount of water but it can and will greatly shorten your DI life. Open the valve each time you start making water and monitor the RO only TDS until it reaches its lowest point before letting it reach the DI and you flush the TDS creep water out so it does not prematurely exhaust your DI resin. It coud extend your DI quite a bit.

Make sure your containers are clean and used only for RO/DI or at least measure your RO/DI TDS straight from the unit an not the storage container so you know it is the container and not the filter. A dirty contaner which was used for a water change isn't the end of the world where contaminated water could be and you need to be able to distinguish between the two.

I second AZ, after doing water filtration for supermarkets, residential is cake.

There is a bypass on the waste water for flush. I don't know anything about the DI bypass. I haven't given much thought about TDS until recently. I was wanting to compare our unit to what we get at Culligan refill for our drinking water.

I'm not concerned about the jugs getting mixed for anything else. I use only the 2 jugs for water changes/refills. I'm also not overly concerned with those numbers. As long as I'm getting better than our TAP and currently better than Culligan, that's all that concerns me.

The bypass is just to flush the membrane aka water in and out, no pressure to push water into the membrane to filter the water. You need the flow restrictor to do this work and the bypass on the waste water does the opposite.

I just wanted to emphasize what AZ said above by bolding and underlining it. If you don't want TDS creep, drain the initial start of the water that is filtered before the DI. Also, how much TDS creep you get is dependent on water pressure. I run a booster pump so it takes 1-2 minutes to get it down to 1 TDS before the DI.

One last thing, if your referring to the Culligan water filters at Walmart/supermarkets they are periodically changed and run on the same set up as many of us reefers have but with booster and permeate pumps going to a water storage tank so its ready to go when a customer wants to vend. It's just commericalized for your convience. :wink:

 

[MrDJeep123]

I second AZ, after doing water filtration for supermarkets, residential is cake.



The bypass is just to flush the membrane aka water in and out, no pressure to push water into the membrane to filter the water. You need the flow restrictor to do this work and the bypass on the waste water does the opposite.

I just wanted to emphasize what AZ said above by bolding and underlining it. If you don't want TDS creep, drain the initial start of the water that is filtered before the DI. Also, how much TDS creep you get is dependent on water pressure. I run a booster pump so it takes 1-2 minutes to get it down to 1 TDS before the DI.

One last thing, if your referring to the Culligan water filters at Walmart/supermarkets they are periodically changed and run on the same set up as many of us reefers have but with booster and permeate pumps going to a water storage tank so its ready to go when a customer wants to vend. It's just commericalized for your convience. :wink:

I'm aware of this part. Before the RO/DI that's where we got our fish water. I always looked at the maintenance record and it was always fixed monthly. If there was a gap, I call the company and it gets sorted right away. I was looking into making the RO our drinking water from our unit instead of having to buy refills.

 

[AZDesertRat]

Maintenance on a vending machine is usually a wipe down with a bleach rag and maybe changing the sediment and carbon filters. Since most are intended for drinking water TDS really isn't an issue since it is the mineral content that makes the water taste good. If you plan to purchase water from a machine always use a handheld TDS meter to confirm the quality before filling your jugs, often you are not getting what you think you are. If Imust purchase large amounts of water I prefer a staffed water & ice type store where the owner or manager is almost always glad to pull their TDS or conductivity meter out and test it in my presence once I tell them what the water is to be used for.

 

[81Shaun]

I agree with installing a ball valve. I picked up a 3 way ball valve for my drinking water and install as az suggested and truthfully I was amazed at the TDS creep I avoided that would be exhausting my DI. I first thought 20 bucks for something like that is a little steep but it was worth every bit of the price.