Which filter first?

[t5Nitro]

For an RO/DI unit I always forget which goes first because they look exactly the same.

First is the micron.
Second is the MARTIKX CTO/2 CARBON BLOCK FILTER

or the MATRIKX +1 CARBON BLOCK FILTER CHLORINE GUZZLER?

Is that order correct or flip the last 2?

I also just checked the TDS coming out of the RO and it came up 52-66. The tap water TDS is around 250. How do I know if it is time to replace the membrane or not? I ordered one and I have it here if I need to.

[t5Nitro]

TDS coming out of DI resin is at ~30 by the way. If that helps in explaining if the RO membrane is needing to be replaced or just the resin.

Thanks.

[MTB]

I would swich the resin and see what the TDS is. If it is at 0-1, I would leave the membrane till you do your pre-filters again. That's what I would do, let's see what others have to say...

[SABOB]

Your RO out should be 90% - 98% of your tap water.If tap is 250 then after RO should be 25.Membrane should be replaced if not in rejection rate of membrane.DI should bring RO down to 0-1 ppm

[t5Nitro]

So I need to replace the membrane or no? I'm at 50+ out of RO and 90% of 250 is 225. Leaving 25 TDS left... so since my RO water is double that it needs replacing? That is how you look at it? I don't know what the rejection rate is.

[MTB]

Makes sense. My tap is around 550-600 and after RO I'm at ~55. DI brings it down to 0 but my resin only lasted for ~4 months till it creeped to 20. I have the filmtec 100GPD which is rated at 90% rejection.

[t5Nitro]

Just changed to DI for tonight and TDS went down to 0. I'll change the membrane and later this week.

Thanks.

[t5Nitro]

On my first post, does anyone know which of those last two is for the second chamber and which is the third? They look identical so I can't tell. I'm going to program them into my phone when I figure it out. :lol: