Carbon Block Replacement

[Pet Detective]

I use a dow 75gpd membrane, sediment filter, 2 pentek chlor plus carbon blocks and a di chamber, my question is how often should I change those carbon blocks, they claim to be rated for 40,000 g? I make about 160 gallons of pure r.o. water a month, I'd estimate about a 4:1 waste ratio, most advice given says to change every 6 months but that's barley 4,000g of water being put through these blocks, I feel like I'm wasting money and my OCD is through the roof because I keep contemplating that I'm throwing out a less than half used carbon block....makes me insane. I started using the chlor plus filters because sometimes our water authority will add chloramines, usually in the spring or fall, so I decided to not take any chances. I have good results, membrane lasts about 2 years, di needs replaced around 2-3 months typically, I change the sediment filter every couple of months because they are cheap but also important for better water pressure. I guess I just want a semi-definitive answer to my dilemma , which I know I won't get.....it's ok OCD, we'll figure this out....sure, sure we will. Please help?

 

[EmdeReef]

I use a dow 75gpd membrane, sediment filter, 2 pentek chlor plus carbon blocks and a di chamber, my question is how often should I change those carbon blocks, they claim to be rated for 40,000 g? I make about 160 gallons of pure r.o. water a month, I'd estimate about a 4:1 waste ratio, most advice given says to change every 6 months but that's barley 4,000g of water being put through these blocks, I feel like I'm wasting money and my OCD is through the roof because I keep contemplating that I'm throwing out a less than half used carbon block....makes me insane. I started using the chlor plus filters because sometimes our water authority will add chloramines, usually in the spring or fall, so I decided to not take any chances. I have good results, membrane lasts about 2 years, di needs replaced around 2-3 months typically, I change the sediment filter every couple of months because they are cheap but also important for better water pressure. I guess I just want a semi-definitive answer to my dilemma , which I know I won't get.....it's ok OCD, we'll figure this out....sure, sure we will. Please help?

I change every 3-4 months. Makes it easier on the membrane and much easier to change in general. I also buy in bulk on amazon or somewhere and probably not the highest end carbon blocks. 15 bucks every few months for 2 blocks isn’t that much...6 months is probably fine, depends how much RODI you make. I go through 30+ gallons a week just for topoff.

 

[ReefHog]

I imagine it's impossible to know exactly when the carbon is spent. I change my prefilters every other DI change just to make things easy. The DI changes color so it's easy to know when it needs replacement.