ro or ro-di

[soggybongo]

hope soeone can chime in and point me in the right direction.

i have a really good ro-di auto cut off unit however i have disconnected the di pod from as i wasnt sure if it is needed. my tds is 0.04 without the di pod and 0.00 with it installed so not a massive difference.
do i use just the ro or do i use ro-di as im wanting to keep my tds in my tank low 100 - 150 throughout the week

my tank specs can be seen here - www.ukaps.org/forum/threads/four-stone-modified-fluval-flex-57.53716/

if using the di pod/ resin do i need to add anything extra remineralising other than what i already use?

 

[soggybongo]

should have mentioned all filters and membrane are new, well a few weeks old. i have run roughly 2000ltrs through the unit so will be broken in by now.

 

[X3NiTH]

I wouldn't worry about removing trace elements from the water using the DI unit as the APF EDTA Traces your adding back have all the main essential trace elements plants need.

For comparison I have copper pipe supplying my RO/DI unit (as you do also), I run the tap above where my DI unit is connected (domestic supply in house) for a few minutes to flush any extra ions in the water that have accumulated over time while the water has sat unmoving in the pipe (am assuming its copper ions, but if I don't do this then the TDS can be more than 10 points higher when I first run the filter). I have also put my DI unit on a bypass so that I can run without it for a few minutes until the TDS drops to 1 out of the RO filter, mainly to increase longevity of the resin (roughly about 10,000L of 1TDS water through it before it exhausted).

Supply pre flush TDS 45-50
Supply post flush TDS 30-35
Supply post RO unit TDS 1
Supply post DI unit TDS 0

If the cost to replace filters in the RO unit and the resin in the DI unit is no big deal then you can forego the flush and bypass stage and get 0TDS immediately.

Good to see you you've gone down the DIY remineralisation route after discovering you were dropping a pile of cash on 100ppm of sodium you didn't need.

 

[soggybongo]

I wouldn't worry about removing trace elements from the water using the DI unit as the APF EDTA Traces your adding back have all the main essential trace elements plants need.

For comparison I have copper pipe supplying my RO/DI unit (as you do also), I run the tap above where my DI unit is connected (domestic supply in house) for a few minutes to flush any extra ions in the water that have accumulated over time while the water has sat unmoving in the pipe (am assuming its copper ions, but if I don't do this then the TDS can be more than 10 points higher when I first run the filter). I have also put my DI unit on a bypass so that I can run without it for a few minutes until the TDS drops to 1 out of the RO filter, mainly to increase longevity of the resin (roughly about 10,000L of 1TDS water through it before it exhausted).

Supply pre flush TDS 45-50
Supply post flush TDS 30-35
Supply post RO unit TDS 1
Supply post DI unit TDS 0

If the cost to replace filters in the RO unit and the resin in the DI unit is no big deal then you can forego the flush and bypass stage and get 0TDS immediately.

Good to see you you've gone down the DIY remineralisation route after discovering you were dropping a pile of cash on 100ppm of sodium you didn't need.

thanks for your reply X3NITH mate will save me a few quid in resin refills. might aswell use it till exhausted.

 

[alto]

Depends on how your system is set up - commercial lab system I ran, we used prefilters, then series of DI, then carbon, then RO membrane ... this gave us the water quality needed & also best longevity of the (very expensive) RO membrane