RO unit help for a newbie

[OscarHaglund]

I am just getting into the hobby and I have gotten a second hand RO unit I need some help with.

Its a 5 stage unit but I don’t really know what it consists of other than the sediment filter and RO membrane.

I started it up and let it run for five minutes and the tds before the RO membrane shows 180 and the output shows 8.
8 seems like its a bit too high and a thing that confuses me is that the preassure gauge does a quick jump when water first flows into the system but after one second it returns to zero. I can clearly bith hear and see the motor in the pressurisation unit working but its not showing up.

Any tips about what could be wrong and what I should be doing?

additionally, is that an automatic flushing system next to the preassure restrictor or should I be adding another line there for a flush valve?

 

[KrisReef]

Let me help.
8/180 = 0.044444 (if I did the math correctly?)

That is a rejection rate of better than 95% running through the ro membrane. That is very good. Now send it through the DI resin and you should easily get zero. The unit seems to be working.

 

[Woodyman]

Most aquarium 5 stage consist of either 1-sediment, 2-carbon, 1-RO, and 1-DI or 1-sediment, 1-carbon, 1-RO, 2-DI. It can also be slightly different than those, but typically that's how most 5 stage are plumbed.

Do you know when any of the filters where last changed?

You have a rejection rating of 95.6% so it would be in your best interest to replace your RO membrane. You can still use it as is, but it will lead to more consumption of your downstream DI resin.

Is there a valve to manually flush the unit?

 

[Woodyman]

It does appear to be an auto flush but I'm not familiar with your unit to know for sure.

No pressure leads me to believe you may be flushing the membrane. The membrane should build pressure to produce permeate water. It could also be a bad gauge, but I wouldn't expect it to show any pressure if it was bad.

 

[OscarHaglund]

Most aquarium 5 stage consist of either 1-sediment, 2-carbon, 1-RO, and 1-DI or 1-sediment, 1-carbon, 1-RO, 2-DI. It can also be slightly different than those, but typically that's how most 5 stage are plumbed.

Do you know when any of the filters where last changed?

You have a rejection rating of 95.6% so it would be in your best interest to replace your RO membrane. You can still use it as is, but it will lead to more consumption of your downstream DI resin.

Is there a valve to manually flush the unit?

I have no idea when they were last chnged but looking at the colouration of the sediment filter I think it looks like its not too bad (maybe).
The TDI measurements were before the RO membrane and after the final filter (maybe DI resin?).
I will move the probes around a bit to see what the TDI is after the membrane and before the DI

 

[polyppal]

8 is just fine, though I’d replace that sediment filter just by looking at it

 

[OscarHaglund]

8 is just fine, though I’d replace that sediment filter just by looking at it

Right, I will do that as well then. How do you know when to replace the carbon blocks?

 

[OscarHaglund]

Strange, when i tested it today the pressure went up and output tds (after di), if thats what i have) went to 3

 

[OscarHaglund]

Plugged the tds into either side of the last filter (after the RO membrane) which I guess is the DI. Turns out the water going into this filter has a TDI of 2 and out comes 4… so thats interesting.