RODI flushing question

[Fishingandreefing]

So I am using an aquaticlife 100GPD 4 stage unit with a the aquaticlife booster unit. It has a built in flushing function which it flush for about 10-15 seconds at initial production of RODI.

What I have found is that after it flushes, it shows 1tds then slowly increases to 5, then it will drop down to 0 at 1/4 of a gallon.

The DI filter is being over 3 months already, and I usually I replace it.

But it I let it drain to a container for the first 1/4 gallon, and it drops to 0, why I am changing the DI filter by wasting money? Am I missing something?

 

[jsmkmavity]

Rodi's need to flush out for at least 2-5 minutes (depending on gpd output) IMO on each startup to flush out from sitting stagnant before producing pure water. The di resin doesnt need replaced until it changes color.

 

[Fishingandreefing]

Rodi's need to flush out for at least 2-5 minutes (depending on gpd output) IMO on each startup to flush out from sitting stagnant before producing pure water. The di resin doesnt need replaced until it changes color.

So let get that color equation out of the picture, if what I mentioned above, if it continue to show zero, there shouldn’t be any harm correct? Assuming that the tds meter is correct which it shows consistent that every time I changed out the di filter, it shows zero.

 

[Fishingandreefing]

And is there a way I can set the booster unit to a longer flush?

 

[jsmkmavity]

So you cant see the di, just changing it based on use/time?
The tds will drop to zero with longer flush time. I do mine manually and i dont know about resetting the automatic timer.
The tds can read zero but they arent very sensative to low tds. The di resin can remove more than the tds meter will register.

 

[Fishingandreefing]

So you cant see the di, just changing it based on use/time?
The tds will drop to zero with longer flush time. I do mine manually and i dont know about resetting the automatic timer.
The tds can read zero but they arent very sensative to low tds. The di resin can remove more than the tds meter will register.

So basically just change it on th peace of mind

 

[Fishingandreefing]

I feel like it’s a scam if I flush for 2-3 mins and the di filter is removing all the tds and giving me zero tds RODI why am I wasting 20 bucks.

 

[jsmkmavity]

The tds meter cant read a lot of what the di resin is removing that lab grade equipment could read.

 

[DanyL]

TDS meters are accurate enough to base your DI replacement on and what most reefers do in practice, don’t worry about it.

About flushing - unfortunately it’s very misleading. Most of the commercially available auto flushing you see is for the waste line. Something that should in theory help preserve your membrane for longer, and be done *after* using it, as well as during long usage. For most use cases, it doesn’t add much if you have a proper restrictor in place.

What you are experiencing is a TDS creep on the permeate line, this happens due to the ionic imbalance between the waste and clean sides of the membrane, which when inactive tries to reach equilibrium, leading the permeate to start with a higher TDS for the first few minutes.

A lot of reefers have a T-Split before the DI, with a valve that goes straight to waste to bypass it, and we use it to flush until we see it stabilize using a TDS meter (or blindly for a few minutes).

 

[Fishingandreefing]

TDS meters are accurate enough to base your DI replacement on and what most reefers do in practice, don’t worry about it.

About flushing - unfortunately it’s very misleading. Most of the commercially available auto flushing you see is for the waste line. Something that should in theory help preserve your membrane for longer, and be done *after* using it, as well as during long usage. For most use cases, it doesn’t add much if you have a proper restrictor in place.

What you are experiencing is a TDS creep on the permeate line, this happens due to the ionic imbalance between the waste and clean sides of the membrane, which when inactive tries to reach equilibrium, leading the permeate to start with a higher TDS for the first few minutes.

A lot of reefers have a T-Split before the DI, with a valve that goes straight to waste to bypass it, and we use it to flush until we see it stabilize using a TDS meter (or blindly for a few minutes).

If I understand you correctly, as long as I flush it til I see zero, I can continuously use this DI filter without replacing it correct?

 

[DanyL]

If I understand you correctly, as long as I flush it til I see zero, I can continuously use this DI filter without replacing it correct?

You flush it until it stabilizes, in most cases you won’t see zero after the membrane (before the DI)

And yes, you can use the DI as long as you see 0 PPM after the DI.

 

[Fishingandreefing]

You flush it until it stabilizes, in most cases you won’t see zero after the membrane (before the DI)

And yes, you can use the DI as long as you see 0 PPM after the DI.

Great. Thx

 

[Idech]

I feel like it’s a scam if I flush for 2-3 mins and the di filter is removing all the tds and giving me zero tds RODI why am I wasting 20 bucks.

I have the exact same setting with the booster pump. I don’t even bother with the 1-2 tds, as it will turn up to be 0 overall when you make enough water. It’s not the case when I fill my ATO reservoir because it’s smaller (max 10 gallons) but I believe it’s still negligeable.

 

[Fishingandreefing]

I have the exact same setting with the booster pump. I don’t even bother with the 1-2 tds, as it will turn up to be 0 overall when you make enough water. It’s not the case when I fill my ATO reservoir because it’s smaller (max 10 gallons) but I believe it’s still negligeable.

Gotcha. I had the feeling I am not the only one here experiencing it so I figure I post this to make sure. I simply just have a jug and flush it for 2-3 mins til zero as mine goes up to 5-6, then drops down to zero. Usually I replace them when it reads above 3 but I guess now I am keeping this method.

 

[Idech]

Gotcha. I had the feeling I am not the only one here experiencing it so I figure I post this to make sure. I simply just have a jug and flush it for 2-3 mins til zero as mine goes up to 5-6, then drops down to zero. Usually I replace them when it reads above 3 but I guess now I am keeping this method.

That really is the best way to go but I don’t have the patience as I need to make rodi 3-4 times a week.

 

[Fishingandreefing]

That really is the best way to go but I don’t have the patience as I need to make rodi 3-4 times a week.

Gotcha lol. Weekly for me but I do have to make them few times a week to fill ATO reservoirs for my 6 tanks.

 

[DanyL]

I have the exact same setting with the booster pump. I don’t even bother with the 1-2 tds, as it will turn up to be 0 overall when you make enough water. It’s not the case when I fill my ATO reservoir because it’s smaller (max 10 gallons) but I believe it’s still negligeable.

The problem isn’t necessarily with the TDS after the DI (which is usually negligible in large quantities), but rather that it burns the DI too fast.

For example, in my setup where I get my tap water TDS up around 780 in the winter, the TDS creep after the membrane (before the DI) can go as high as 200-300 ppm, leading to fast DI depletion.

Since I started flushing the TDS creep before the DI, I went from a couple month lasting DI, to 4-5 months. That’s a big a difference, not even money wise - but rather in maintenance.

 

[FernBluffReef]

So let get that color equation out of the picture, if what I mentioned above, if it continue to show zero, there shouldn’t be any harm correct? Assuming that the tds meter is correct which it shows consistent that every time I changed out the di filter, it shows zero.

Also don’t confuse flushing the RO filter with flushing the system. The RO filter needs to be flushed on occasion, as you mentioned yours has an auto flush valve. There is also something called TDS rebound where water sitting in the filters re-absorb (best I can describe) some of the TDS. So every time you start the system you also need to just waste the first 5-10 minutes of production before it goes into your DI else your needlessly burning expensive media. I batch produce RO/DI as much as I can to be most efficient on media

 

[Chuck_e]

TDS meters are accurate enough to base your DI replacement on and what most reefers do in practice, don’t worry about it.

About flushing - unfortunately it’s very misleading. Most of the commercially available auto flushing you see is for the waste line. Something that should in theory help preserve your membrane for longer, and be done *after* using it, as well as during long usage. For most use cases, it doesn’t add much if you have a proper restrictor in place.

What you are experiencing is a TDS creep on the permeate line, this happens due to the ionic imbalance between the waste and clean sides of the membrane, which when inactive tries to reach equilibrium, leading the permeate to start with a higher TDS for the first few minutes.

A lot of reefers have a T-Split before the DI, with a valve that goes straight to waste to bypass it, and we use it to flush until we see it stabilize using a TDS meter (or blindly for a few minutes).

Mine will jump to 40-50 when it first starts, then slowly come down to 0 until after about 4 minutes. It's very consistent, to the point that I've set up a tee like you described with a solenoid switch on each side, controlled by Apex. The valve on the "product" leg is closed and the "waste" side open for the first 4.1/2 minutes, then they switch. I use timers & virtually outlets to manage this, and will spot-check from time to time to make sure the TDS is 0 when they switch. I'll make around 7 gallons 3-4 times per week for the ATI reservoir, also controlled by Apex using a combination of optical sensors, timers, and virtual outlets, and then more if I decide to do a water change. So far, so good...

 

[Fishingandreefing]

great that this is the norm. I used to replace the di every three months when first turn on and it reads above 3, now I will flush it for a few minutes til drops to 0.

I will replace it when it reaches 1-2 steady after flushing for a few mins

Thanks for all chimes in