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Changing R/O filters

Hi folks,

About 2 years ago I got tired of lugging jugs of water home so I bought an R/O and think it's great but I'm wondering if I should change the carbon block or TFC membrane yet? The manual (a xeroxed sheet) said when the flow of good water is reduced it needs replacement but I can still make a 5 gallon pail in about 2.5 hours which is what it has always produced since I got it.

I've done the math and on average I make 20 gallons per week for 104 weeks is only 2080 gallons. Is it time to change anything or can I chill?

BTW my water at last testing some time ago) was a PH of 7.4 out of tap but has a high carbonate hardness due to the apartments sodium softening... if that matters in judging replacement.

Thanks for any thoughts!  
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[b said:
Quote[/b] ]I've done the math and on average I make 20 gallons per week for 104 weeks is only 2080 gallons. Is it time to change anything or can I chill?

It depends if you can "chill" If the tap water you're filtering has a very high TDS level then filtering 2080 could require you to change the filters.

[b said:
Quote[/b] ]About 2 years ago I got tired of lugging jugs of water home so I bought an R/O and think it's great but I'm wondering if I should change the carbon block or TFC membrane yet?


The RO membranes and carbon block can last a long time if you're filtering water with a relatively low TDS rating (for tap water that is). So what you can do is get a TDS meter and test the water before it is filtered and record the readings then test some water thats gone through the RO unit thats been filtered and record the TDS readings. Then figure out how much of an increase there is in total dissolved solids (TDS). Then if the TDS reading is higher then what it is supposed to be with good filters then you need to replace them.

On my spectra pure 5 stage RO/DI nit I usually replace the RO filters (carbon and membrane) every two years. I have yet to need to replace the DI element but its supposed be every 5-8 years depening on usage.

hope this helps
 
I'd say just replace everything except the RO membrane and don't worry aobut it. If the carbon filters get too old the the chlorine can get past them and tear up the RO membrane.
 
if you want higher product water, get a larger membrane. I used to be able to fill a 5gallon jug overnight with the 8GPD membrane, witht he new (2-3 month old) 25 GPD membrane I have to watch out, I've overlfoed 2 buckets already! Carbon blocks need to be replaced every 6-8 months I say, I have a very high chlorine level in my area and have to be careful to watch my filter changing times, I don't want my new membrane to be destroyed! But if you notice a very slow making of RO water generally, you need to replace the membrane.
 
Thanks guys it seems to depend upon a lot of variables maybe I better just replace them both (and begin replacing the carbon a whole lot more often!).

Nep G. how do you know how much chlorine is in your water and how do you know if your filter membrane has been destroyed from chlorine? Will the good water smell like chlorine? Mine doesn't, but I'm just wondering cos the "manual" which came with my Captive Purity brand R/O was pretty worthless - basically it just showed how to hook it up to your sink and said thanks for buying it!
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Another thing I've wondered about is using R/O water all the time good enough or should I occasionally flush the pots with pure distilled water? When I used to buy water I would alternate between R/O and distilled but now I haven't done so in almost 2 years.
 
RO water isn't 100% pure so in the long term minerals can still build up. I would suspect that normal repotting schedule would remove this threat however as old mix is replaced with new. Will it help to flush? probably only minimally.

How often the carbon needs to be replaced depends greatly on the carbon filter itself, the Chlorine levels in the source water and how much the filter is used. A good carbon filter is rated to handle x many gallons of water before replacing. Calculating lifespan is no more difficult than calculating how much water is used to produce a set amount of purified water.. ie catch the purified water and the waste water and see what the ratio is. Then you can calculate lifespan based on how much water you make per day.
Or just use a quality carbon block filter and replace it periodically and your most likely not going to have a problem.

Chlorine will punch holes in the RO membrane. You may get some chlorine smell in the ro water but I think only in extreame circumstances. A bigger concern is this allows other molecules to pass through that shouldn't. The result is the quality of the RO water will decrease and it's TDS will increase. This will also happen slowly as the membrane ages.
Tony
 
Josh, to check how much chlorine is in your tap water, have an analysis done or just check with your Dept. of Water Dist.

I did have a measurement but I lost it. I generally check every year or so, in the summer it increases due to heavy tourism.
 
Thanks folks! I guess my tax refund is going for supplies this year!
 
<span style='font-size:12pt;line-height:100%'>My suggestion would be to check the TDS of your feed water (the water that goes into and through your R.O. membrane) and the TDS of your product water (the water you collect to use on your plants). The product water should be dramatically lower in TDS than the feed water. You should replace your R.O. membrane if your product water is higher in TDS than the purity you have decided to use on your plants. Or, if the degree of purity produced by a new membrane does not meet your needs, then you should consider alternative purification or augment your R.O. system with additional stages of purification, i.e. deionization, distillation, etc.

Remember that TFC (Thin film composite) R.O. membranes are very sensitive to any chlorine in the feed water. It can quickly damage or destroy them. The carbon prefilter is there to remove the chlorine before it gets to the R.O. membrane. If the carbon filters' capacity to absorb chlorine is exceeded, the TFC R.O. membrane can quickly be damaged or destroyed.

Using a TDS meter regularly is the only way to be sure you are not watering your plants with feed water.</span>
 
  • #10
what's an acceptable TDS level for water used on CP's?
 
  • #11
My water supply recently switched from Chlorine to Chloramines. Does anyone know if this is better or worse for R/O membranes? Or for CPs?

Capslock
 
  • #12
Dyflam, generally all CP besides Nepenthes need water within the 0-15ppm range.

Nepenthes can take 0-100ppm but if it is in the higher limits I would suggest repotting every year or two. I think my water is around the 5-8ppm range last I had it checked.
 
  • #13
We change the filters on a regular basis-the carbons and sediment every ten months or so, and the big membrane every two years. We've never had a problem. Every two months or so I back flush the sediment and carbon filters and get some really nasty looking effluent when I do this. I carefully run the water backwards and forwards until I get clear water running out, making sure to run the water in the proper flow direction the last time I flush and put back in line. Afterwards, the RO setup seems to work faster.
Another maintainence tip that may help...
Trent
 
  • #14
Does anyone have a diagram showing how idiots can change filters? Somebody set one up for me and I have no idea what is what, lol.

Joe
 
  • #15
Ha! Pretty much the same with me Joe! I lost my "instruction manual" (the one sheet) and only have the "old people's Jar opener" tool to unscrew the canisters. I believe my 3 stage unit is as follows: first stage is the dual density sediment prefilter, first bottom canister carbon block prefilter and 3rd canister is the 75 GPD TFC membrane.

Trent, I bought one of those "Flush kits" with my R/O unit but when I inquired about how to use it about 2 years ago nobody seemed to know what I was talking about so I never bothered trying to figure it out. Can you explain how to attach/use it? I bought a Kent marine flush kit which basically looks like a mini-ballvalve with an extra hose.
 
  • #16
Oh my loard...old peoples jar opener
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Joe, basically the canister sumps unscrew, you cahnge them and the membrane housing just unseals with a turn or a button push, no biggie.
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Josh the flushkits allow more water to pass over the membranes, but I belive (from a friend
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) that all you need to do is take out the flow restrictor and let the unit run awhile, this allows more water to go thorugh the units and carrys excessive minerals from the membrane with it.
 
  • #17
Basically, I use the raw feed line and take the sediment and carbon filters out of the lineup and put the raw feed in backwards. I run it a minute until the dirty stream looks a little better. Then I put the raw feed back to the way it should be and flush again. i repeat this process until i get clear water when hooked up in proper sequence. It is important not to feed any chlorinated tap water into the membrane filter. Obviously, I run just the sediment and carbon for several minutes before hooking them back up to the membrane filter. This is hard to explain, but very simple to do!
 
  • #18
Trent, So basically you take the RO apart and hook it back up backwards to flush it?

I've ordered all new cartrdges (sediment, carbon and membrane) the combined total was just slightly less than buying an all new 75 GPD RO unit!
Do the replacement cartridges generally come with descriptions of how to perform the replacement task? I definately wanna make sure it's put together right and is watertight when I go to turn it back on.
 
  • #19
heres a moronic question

how do you check the pp of your water

maybe my water from the faucet is actually the water i can use to water my plants, but i just dont know it yet!
 
  • #20
<span style='font-size:12pt;line-height:100%'>Generally I like to keep mine below 10ppm. 1ppm or lower is what I usually get. But I grow most of mine in what would be considered a closed system. Where they are in undrained trays and any minerals (TDS) that are in the water will wind up in the trays and pots. Basically what this means is that every time I water my plants I am adding the minerals that are in that water to the system, and then again the next time I water, eventually the minerals will build up to undesirable levels and I will need to either leach the excess minerals by washing lots of pure water through the pots and down the drain, or repot everything affected into new media. I usually wind up doing the repot into new media exercise, more work
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but more reliable at producing satisfactory results.</span>
 
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