how often to wash the ceramic sediment filter for RODI unit ?

[chercm]

anyone ? how often ?

[solitude127]

I replace my sediment filter at least every 6 months if not sooner.

[gonpostal]

I replace my sediment and carbon filters when I get a TDS reading of 1.

[nemosworld]

I think it's important to note your usage when giving advice on subjects like this.
reason being: everyone has diff tank sizes and evaporation rates, as welll as water changes. if you have a nano tank, your usage will be far less that someone with a large reef. so your carbon, sediment and di usage and expiration will all be diff. i read somewhere that you should change the sediment every 3 months. i don't do it though.

i also read that when you start to lose water pressure, it's time to change the sediment. i'm no expert, so i can't give advice. maybe contact a pro such as BRS. they give great advice without trying to get you to buy their products.

[Mike31154]

I've never come across a 'ceramic' sediment filter? Washable? This means it can be reused? Please provide additional info on this.

I run a 5 micron poly prefilter followed by a 1 micron poly prefilter, then carbon block followed by the RO stage. I find the 5 micron poly gets grungy fairly quickly with my 210 or so TDS tap water. On occasion I've removed & scrubbed the 5 micron poly filter with a nylon brush & put it back into use rather than replacing it. This has worked quited well actually since the grunge was mainly on the extreme outer layer of the filter. I sliced one open after having done this a number of times and found the grunge had not penetrated very far into to core of the filter. Seems like a waste to change these out too often, even though they don't cost much. I monitor my system with two pressure guages, one before RO membrane & one at source. This provides a pressure differential number that allows me to tell when it's time to look at the prefilter(s). Worth noting also that the 1 micron poly has been in there for better than a year and shows little change in coloration, so the 5 micron appears to be picking up most of what's coming in with regard to visible sediment.

Anyhow, I'd be very interested in hearing more about the possibility of replacing the 5 micron poly pre filter with a ceramic version that can be washed & reused more often.

[AquaticFins]

As nemosworld stated, a sediment filter should generally be changed/cleaned when a pressure loss is observed. That's really the only way to effectively measure their life.

For what it's worth, the original poster isn't asking about the disposable spun or wound polypropylene cartridges that most of us use. The ceramic cartridges the original poster is referring to are usually made of diatomaceous earth - as they clog, you scrape off the top layer and you have a fresh sediment filter again. They are typically far finer than PP cartridges and therefore clog more rapidly. Even if you used the same amount of water and had the same incoming water quality, how often you replace your PP cartridge won't have much of any bearing on how often a ceramic cartridge needs cleaning.

To Mike31154, they're not especially common in the aquarium industry, but certainly popular enough in other water purification uses. Since you're removing material each time you clean them, they don't last forever - typically, you replace them when they're down to ~1.5 inches in diameter. That depends on manufacturer, of course. Overall, they will last longer than polypropylene cartridges...but you have to break the unit down and clean them much more frequently. They're also far more expensive.

[JohnM99]

How often you need to change filters / clean them depends upon 2 factors -
- Source Water Quality
- Usage

When it is clogging you will see your pressure drop, time to fill a container increase and TDS meter readings start to rise. Hugely variable depending upon how bad your source water is. So, no fixed time.

[Buckeye Hydro]

I run a 5 micron poly prefilter followed by a 1 micron poly prefilter, then carbon block followed by the RO stage. I find the 5 micron poly gets grungy fairly quickly with my 210 or so TDS tap water.

Remember that "TDS" is total DISSOLVED solids

What the sediment filter catches is TSS - Total SUSPENDED solids.

Russ

[Mike31154]

Remember that "TDS" is total DISSOLVED solids

What the sediment filter catches is TSS - Total SUSPENDED solids.

Russ

Good info & clarification. I guess I made the assumption that any rise or fall in TDS would naturally be associated with a rise/fall in TSS which is most likely inaccurate & would depend on every individual's source water. Although my post was more about what can be done with prefilters to stretch longevity, you are correct that the TDS reference can be misleading in that context. Thanks.