Need advice on whether it's time to replace original filters in Spectrapure Maxcap 5 stage RODI...

[blackstallion]

I have a 200g reef tank. Been running the RO/DI for 1 year with the original filters; unit is configured for 90GPD.

Tap water is fairly low TDS at 60-80ppm.

I'll typically get between 53psi-58psi pressure.

1 year of RO/DI product water = about 1800g between WC's, ATO and QT tanks.

Took some measurements today and trying to determine if it's time to replace any filters.

1) Waste water : product water @ 53psi = 2.5:1
2) Measured TDS Output vs Input = 47:0
3) RODI product water calculated at 2.74GPH/65.76GPD
4) 0 chlorine tested at waste water (see test strip)

 

[dwest]

I can tell you what I do.

First, that’s a low TDS and a great RODI system.

I have a 180 gallon tank and do 1% daily AWC. Same RODI unit. My inlet tap water is about 150 TDS but about 90 psig. I replace my sediment and carbon filter every 6 months. I replace the DI membranes when TDS directly out of the cartridge goes above zero. (I get 1-2 years out of first cartridge and several years out of second). I plan to replace the membrane when rejection rate below 95%.

It looks to me like you don’t need to replace membrane or cartridges because TDS is zero. However, I would consider replacing the sediment and carbon prefilters.

 

[blackstallion]

I can tell you what I do.

First, that’s a low TDS and a great RODI system.

I have a 180 gallon tank and do 1% daily AWC. Same RODI unit. My inlet tap water is about 150 TDS but about 90 psig. I replace my sediment and carbon filter every 6 months. I replace the DI membranes when TDS directly out of the cartridge goes above zero. (I get 1-2 years out of first cartridge and several years out of second). I plan to replace the membrane when rejection rate below 95%.

It looks to me like you don’t need to replace membrane or cartridges because TDS is zero. However, I would consider replacing the sediment and carbon prefilters.

I'm reading 1ppm right after the RO membrane, and 0 right after both the DI stages.

I'm curious as to why you suggest changing out the sediment and carbon filters? Is it just precautionary?

From my understanding, once the PSI drops significantly, it could be a sign the sediment or carbon filters are clogged. And I also have read if there is chlorine present in the waste water, the carbon filter needs to be replaced.

But I'm open to changing both since I want to prolong the membrane and DI filters.

 

[homer1475]

Ive just gotten in the habit of changing all 3 when when I change DI(sediment, carbon, DI). I find it just easier to buy the kit, and change them all.

My water is fairly clean though @ 24TDS incoming, 0 to 1 into my DI. So I get quite a bit of life out of a DI canister.

 

[dwest]

I'm reading 1ppm right after the RO membrane, and 0 right after both the DI stages.

I'm curious as to why you suggest changing out the sediment and carbon filters? Is it just precautionary?

From my understanding, once the PSI drops significantly, it could be a sign the sediment or carbon filters are clogged. And I also have read if there is chlorine present in the waste water, the carbon filter needs to be replaced.

But I'm open to changing both since I want to prolong the membrane and DI filters.

Good questions.

I suppose my replacement schedule is mostly precautionary. I replace the carbon filter at 6 months because chlorine will damage the RO membrane. I am concerned that once I determine there is chlorine in the RO water by measurement, it might be too late. At that time, I replace the sediment filter as well. I buy the filters in bulk so the cost per replacement is relatively small.

I just took a look at the manual and it does indicate that 4-6 months is typical for both sediment and carbon prefilters. It does also state that using the pressure gauge, as you do, is appropriate for the sediment filter. So I say do what works for you.

I would say one more thing. I have been reefing for over 25 years. I’m on my 2nd Spectrapure RO system. I‘ve tried many “cheaper” replacement cartridges and DI resins. I always come back to using Spectrapure because it’s the most cost effective in the long run for me.

https://www.f3images.com/IMD/UserManuals/SP12291.pdf

 

[dwest]

Tha

Ive just gotten in the habit of changing all 3 when when I change DI(sediment, carbon, DI). I find it just easier to buy the kit, and change them all.

My water is fairly clean though @ 24TDS incoming, 0 to 1 into my DI. So I get quite a bit of life out of a DI canister.

That’s some good water