RO/DI question...

[lkleung007]

I am currently running a 4 stage RO unit for my wilds and have read on another website that the DI resin (stage 4) is really for reefers and is not necessary for freshwater fish like discus... Is this true??

If I were to bypass the DI resin, will the RO unit produce less waste water??

If I can simply bypass the DI resin, I would save a lot of money each year as I go through an 8 lbs bag in about a month and the bags cost around $60 at bulk reef supply.

Thanks for any input,
Lester

[Adam S]

Your TDS without resin will be 8-15, which is fine for freshwater. I don't think the waste water ratio improves.

[lkleung007]

Thanks for your reply!! I'm going to try and go without the DI resin... should save me a lot of money each year.

Regards, Lester

[MendoMan]

I'm going to be watching the answers also. I use RO/DI for my wilds also . When my water enters the DI filter it is down to 5 TDS then goes to zero after the DI. Then I go right back and add enough tap to get my TDS up around 20. Seems like I could skip the DI. That's always the first that needs replacing.

[lkleung007]

Heck, I think a TDS of 5 is pretty darn good... I do my water changes with 50/50 RO and tap mix for my wilds.

[MendoMan]

Heck, I think a TDS of 5 is pretty darn good... I do my water changes with 50/50 RO and tap mix for my wilds.

I'm thinking i'm wasting money on DI resin

[Adam S]

If your tap is good enough to reconstitute the RO, you are wasting money on DI. DI is only useful for excessive nitrate (or phosphate for some applications).

[Hart24601]

Most people don't need DI unless as others have said you have high nitrates (or other compounds RO isn't great at removing) from say living in a high ag area.

You can improve waste water with a 2nd membrane. Bulk reef supply has complete packages or add on kits to add 2nd membrane if your water pressure is high enough:

https://aquarium.bulkreefsupply.com/search?w=water%20saver&asug=