RO/DI filter change - 1 or 5 micron sediment and carbon filters?

[Bobbofin]

Got a BRS 4 stage RO/DI and it's time to change the filters and DI resin. Last time I changed the filters and DI was October 2010, 17 months ago. I know, should be doing every six months but I only make 10 gallons a week of water. RO/DI water tests zero TDS. Getting a little bit of cyano in my tank and think I may have low levels of phosphates getting through. Running SeaChem Phosguard and carbon in a reactor changed bi-weekly and a bio-pellet reactor for years. I'm going to get a phospahte test kit to test the aquarium water.
My questions are:
I have always put high quality 5 micron sediment and 5 micron carbon block filter in it. Will moving one or both up to a 1 micron benefit anything? Also, I have had my RO/DI around three years and probably have run 2000 gallons through the RO membrane, about 10 gallons weekly. What is the lifespan of a RO membrane?

Thanks, Bobby

 

[delta]

start with the larger and go small so 10 micron5 micron 1 micron.

you have to measure you TDS from your supply then right after your membrane. once your are removing under 94% it is time for a new membrane

 

[SteveDola]

By putting a lower mircon filter infront of the RO membrane it will prolong the life of the membrane... as not as much will pass through the 1 micron filters. I think that with your lower useage a RO membrane would last about 5 years but test the output regularly.

On a side note, running lower micron filters will stop a lot more but also quickly deplete the filter thats why I run 5 stages to have that first initial stage to catch the big stuff and save the smaller particles for the smaller micron filters. I usually run a 1m sediment, .5 sediment, .5 carbon, RO, DI. IMO the 5 micron filters dont catch enough and would rather replace more regularly. I suppose I could add another prestage for a 5 micron to help prolong other filter lives but usually its the sediments that need replacing and theyre relatively inexpensive online.

 

[Bobbofin]

I only have a 4 stage RO/DI; sediment, carbon, membrane, di. I have always just ordered the $21.99 kit from BRS with a 5 Micron Purtrex sediment filter, MATRIKX + CTO®/2 Carbon Block (5 micron) and Color changing DI Resin refill.

Would it benefit me to order 1 micron filters and change them every 6-8 months instead of every year and a half? I have a reef/home unit with a auto shut off valve, check valves, a 3 gallon RO tank with sink faucet. Usage is pretty low; 6 gallon water change weekly, top off water and drinking/cooking water(RO only). I use probably 10 gallons RO/DI and 5 gallons RO for drinking and cooking. I have had the unit 2+ years and this is my 2nd filter change.

I am getting 345 TDS out of the tap and 11 TDS out of the membrane which is a 97% rejection rate so membrane still good.

 

[aiaman]

I was led to believe that anything more that 4 TDS from the memberane was too high, is that not the case?
also I was told that to check to see if your 1st stage filters were gone to use a pressure gague at the begining and compare to the end stage, if there is a drop in pressure than those filters are spent?

 

[Bobbofin]

I was led to believe that anything more that 4 TDS from the memberane was too high, is that not the case?

I was always led to believe that membranes had a 98% rejection rate out of the box and the DI took care of the other 2%. When it got down near 92-94% it was time to change it because you'd exhaust your DI too quickly if you didn't. Is the TDS out of the membrane relative to the TDS of the tap water and not a number written in stone? I think so, BRS website states a 98% rejection rate not an actual TDS number.
http://www.bulkreefsupply.com/store...sis-membranes/75-gpd-filmtec-ro-membrane.html

 

[Flame Angel]

Bob, I have a couple of 1 micron filters that I won in the raffle back in November. I will never use both of them in the very near future. If you would like one to test your theories your more than welcome, but would need to come and pick it up. Or snag it from me at the next meeting, although it does not sound like you can wait that long.

I believe in paying things forward and you seem to be the type of person that is helpful to others from what I have seen on the board.

I am curious what you choose to do.

 

[Flame Angel]

For FWIW I have heard both good and bad with going witn 1 micron filters. Besides, I thought you were an engineer or someting like that. Either way I know you are handy and have done some of your own DIY projects.

I guess when you sit down and think about it, common sense would dictate on what is logical. You may go through more 1 micron filters saving the other cartridges, but doesn't the membrane need so much preasure to opperate correctly? Would a 1 micron filter affect that? Makes me wonder. I am still new to all of this, so do not listen to me.

Regardless, I am sure you will come to the right conclusion.

 

[Bobbofin]

I thought you were an engineer or someting like that.

I am actully a food equipment service tech, a carpenter's helper, r/c hobbyist, Christian minister, chief cook and beer quality inspector. Hee Hee

 

[Flame Angel]

So, in short you are over quailified.

 

[Bobbofin]

So, in short you are over quailified.

Most likely!

 

[Ruge13]

Man you guys have it easy I use a 1 Micron sediment Filter in a 4 stage before the carbon block. I have to change that approx every 1 to 1 1/2 months before the TDS starts to creep. Lots of crap coming in my town water. But, at $2 a piece its short money over the course of a year. I rationalize it by assuming I am doing the RO membrane some good.

 

[stingythingy45]

Man you guys have it easy I use a 1 Micron sediment Filter in a 4 stage before the carbon block. I have to change that approx every 1 to 1 1/2 months before the TDS starts to creep. Lots of crap coming in my town water. But, at $2 a piece its short money over the course of a year. I rationalize it by assuming I am doing the RO membrane some good.

Really?
Wow,I have town water and it's like 80 tds right out of the fawcet.
I change my filters like every year.I did however chnage the ro membrane recently to a Dow filmtech.

 

[Ruge13]

I should have also mentioned I am making approx 50 gallons a week between Kalk dosing, ATO, and water change. I recently had our town water tested, I showed high iron (my filters turn orange) due to some old iron piping to the house (this is what the town tells me). You could taste it in the water. After a phone call to the town mysteriously overnight the taste went away and the filter lift is prolonged a bit. They changed something, but claim it was "routine". Either way it is better than it was, but still need to change often. I have a TDS meter but honestly do not remember what the water tested at before I installed the filter.