Slow RO

[LeeH]

I have purchased a 4 stage RO system that I thought was oversized @ 100GPD or 455L/day.

455L/day = 19L/h

I collected 1957ml of RO water and 6783 of waste making it 22.4% efficient which is a little under the googles average of 25%.

The issue is 8L/h is only 192L/day!

TDS is moderately high @ 250 ppm

Thoughts?

https://www.finest-filters.co.uk/100gpd-4-stage-complete-ro-reverse-osmosis-unit/

 

[JT_Brews]

I am not an expert in this at all but from when I looked at it (and tried it with a smaller system) the conclusion was that RO systems don't work very well with hard water without a softening stage first.

 

[Ben034]

I think it will depend on your water pressure firstly. I think if the water is very cold as it would be now, it will also be a lot slower.

I recently got a 3 stage system (50gpd) and I only get 2.5l an hour at the moment. I just leave it on the day before and usually mix with tap unless making a lager.

 

[chillipickle]

As ben mentioned, how is your water pressure?
Last time i used an ro system for my reef tank i needed an in line pump to get the water pressure up.
https://ro-man.com/product/reverse-osmosis-pump/

 

[user 18729]

That TDS isn’t great for a new filter. But then it’s still ideal for brewing

 

[Rob11TC]

Mine is really slow in the cold weather. Used for my reef tank. Is your TDS after the membrane as that seems really high if it is. My 100gpd unit takes about 40-45mins to produce 25l of rodi water if that helps. In summer its approx 30 mins.

 

[Ben034]

That TDS isn’t great for a new filter. But then it’s still ideal for brewing

I read the TDS of 250 as being before going through the system (ie the starting point)?

I think the GDP figure is for water at 20c. As water cools the holes in the membrane shrink and therefore the water passes more slowly.