Discussion in 'Water Chemistry' started by Swisswiss, Feb 18, 2014.
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Hahaha. Man we had a stumper going lol. Well its good to know you found the problem, even if it was a facepalm lol.
As far as filters go, sediment filter goes first then granulated carbon, then another granulated carbon or "block" carbon (I don't remember the correct name). I use two granulated carbon filters though. They work just as well and they don't get clogged up if you have a lot of dirt in your water. Also, you won't see a significant drop in TDS after the sediment/carbon filters. So that is not a good indication if the filters are still good or not. Normal operation of an RO would require the filters to be changed once a year. Normal operation would be using it for all drinking water, cooking ice maker, etc. Doing all of these things and filling a 120 gal fish tank would probably mean you need to replace them every 6 months. The membrane should last you 3 years if properly maintained, i.e. not letting chlorine hit the membrane and changing prefilters regularly. You can also install the flush valve kit on the drain line to extend the life a little longer. You may also want to change the DI depending how long it has been running without a membrane.
Glad you got it all figured out!
yeah i definitely need to change the DI membrane, thx for the help everyone glad i got this figured out finally....sigh.....
I know the feeling I have that feeling at least once a week.
Do not use granular carbon. On average a full size GAC filter has a useful life of about 300 total gallons, thats 60 treated gallons and 240 waste gallons at the normal 4:1 waste ratio. Even using two it lasts you about 120 treated gallons. That is a far cry from the 20,000 total gallons a single 0.5 or 0.6 micron carbon block lasts or around 4,000 treated gallons and 16,000 gallons waste. That and GAC products break down or erode as they exhaust leaving a dust or fines which makes its way to the RO membrane causing plugging and fouling. IF you use granular products, catalytic carbon included, ALWAYS follow the granular carbon with either a solid carbon block or a sediment filter no larger than 1 micron in size to trap the fines and dust. Its cheaper than a new membrane. The best is a single carbon block by far though and a one 1.0 microns or smaller is also highly effective at removing the chlorine portion of chloramines.
If you keep up with the 6 month sediment and carbon block replacements and disinfect the system at least annually to kill any bacteria or virus present, and use low micron replacements your membrane can last up to or longer than 10 years, I am over 6 years on my present membrane and its still at better than 99.4% removal efficiency. When i was using higher micron lower quality replacements it was about 24 months membrane life tops.
Don't waste your money on a flush kit, they do noting except lighten your wallet and give you a warm fuzzy feeling. Keep your waste ratio at the manufacturers recommended rate and you are doing all the flushing necessary to keep the membrane fresh. If you want to do something useful, install a simple tee and ball valve between the RO and DI stages, a DI bypass, and flush the TDS creep out each time you start the system. TDS creep is on the treated side of the RO membrane, flush kits are on the waste side so do nothing for this and do not extend the life of your membrane or DI resin.
the three filters i use, when i shake the middle one it sounds as if its granular carbon inside
Pick the center one up and throw it as far as you possibly can, its next to worthless in a reef system. Granular activated carbons were used 25 years ago when RO drinking water systems were first introduced at the consumer level. They have a very short useful life, erode or break down plugging whatever is downstream, and are not very effective at the higher flow rates most reefers RO/DI systems operate at. They were designed for 15 to 25 GPD systems with low velocity and lots of contact time not todays 75-100 GPD and higher flows. Remember, everything including the waste goes through the carbon and sediment filters so its not just 100 GPD, it is 500 GPD with the waste.
Carbon technology has come leaps and bounds in the last 20-30 years. Todays carbon blocks are steam extruded under great pressures using specific blends of carbons to be most effective. The amount of surface area in a carbon block is millions of times more than a similar sized 10" GAC filter.
Look for a sediment filter in the 1 micron range or smaller, I use 0.2 microns myself, and an absolute rated filter is much better than the normal nominal rated filter. Match that with a single 0.5, 0.6 or 1 micron solid extruded carbon block, not two just one. Take the extra empty canister and with maybe $5 in parts and 30 minutes time, convert it into a full size 20 oz vertical refillable DI filter and you have a great reef quality RO/DI system.
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