what is your r/o tds reading


broke but happy
current mine is 5 for the reef and 41 for drinking water
my reef have more purewater than what i drink.lol
how about you guys?


New member
i use rodi and its 0... i dont remember what it is fo just the ro which i use for drinking water... ill have to test it later


New member
How long has it been when you change out the media? Mine has been going up as the media filter and rodi getting spent. My tap is sometimes as high as 500-600+ with 0 reading but lately its been around 350-400.


New member
My tds is 12 for my ro/di. It was zero when I bought it two months ago. Maybe I left the water container outdoor


New member
when i had mine (the filter guys), it was somewhere from 5 to 10 out of RO, and DI stays 0 all the time.


In Memoriam
when your tds gets high what filters do you guys replace.. once my ro/di hits 5 i replace all the filters but the membranes.. which ones do you guys change out


Premium Member
I replace the sediment and carbon block every 6 months. I only change the DI resin when the TDS is 1-2.

Keep in mind the prefilters protect the membrane from damage caused by sediment and chlorine/chloramines. The DI is used to polish the post RO to 0, so the two scenarios are not related. Keep the membrane protected or it will be costly.


Active member
A working RO should get rid of 95% of your TDS before the DI. Savethereef's RO is working perfectly. 442 TDS to 6 TDS before the DI.

RO Membrane that are 90GPD or higher has a 90% efficiency meaning 400 TDS will take it down to 40 TDS and your DI will exhaust faster (3x-5x faster) so swap those membranes for more efficient ones

DI costs more to replace. Membranes are cheaper.

If your TDS is high check the drain line. It should produce 4x waste what your RO produces ie 1 oz of RO water = 4 oz of waste water.

75GPD or lower RO membranes are $25-$45. Get the DOW filmtec brand. Sponsors here sell them but fleabay are the cheapest.


New member
Recently bought a Melev RO/DI and TDS meter.

Tap water: 470
RO: 15
RO/DI: 0

LFS freshwater that I have been using for 5 years: 39

Maybe found the cause of my bubble algae?


New member
Tap water: 510
After RO: 4
After DI: 0

Filters are 6 months old so time to change even with tds readings still pretty good.