ro filter and brass fittings

Discussion in 'Tank Talk' started by robind, Jul 9, 2009.

  1. robind

    robind O. bimaculoides Registered

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    So I bought a used watts premier 'pur-tek' RO filter on craigslist today ($30!). I plan on getting new cartridges for it. However I'm a bit worried about the T fitting on top of the accompanying pressure tank, as it is brass. Does anyone know of a plastic replacement for this particular part?
    Follow up question: it occurs to me that maybe I shouldn't even be using the tank. I'm not 100% on this, which is why I'm asking, but I believe that the tank is a pressure tank so that when it is filled the back pressure will cause the shutoff valve to...shutoff, and then the pressure tank is enough to push the water up to your faucet. Since I'm pretty much just using it to fill the tank, maybe it would be better to have the output of the filter just go straight into the display tank, instead of through the pressure tank (and the brass fitting)?

    Please advise,
    Robin
     
  2. robind

    robind O. bimaculoides Registered

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    I've completed my all-plastic RO setup (though the tds meter has SS probes I suppose), and I'm flushing out the DI cartridges now, though I believe it should be done by now. The TDS out of the RO is reading 7-9, and the TDS out of the DI is always about the same. Do I just need to flush it more? Perhaps my meter needs to be re-calibrated. Any other suggestions?
     
  3. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    I can't help too much with your plumbing questions but with my setup the tank has come in useful. Mine is plumbed so that the tank only receives RO water (not DI) and there is a sink tap that lets me use the RO for other things (like irons and fountains and my neighbor's bird). I use a plastic holding tank and don't have direct top off so it also gives me 2 gallons of water quickly when I empty the RO/DI bucket into the salt mixing bucket.

    When you said you were flushing the DI cartridge, I am not sure what you mean. I replace the sand but I am not sure what you mean by flushing unless you are referring to the carbon prefilters (the DI process is after the RO, the particulates and carbon before). The carbon cartridges are supposed to be flushed when newly replaced but I am not sure there is any real reason for this other than to remove the carbon dust.
     
  4. robind

    robind O. bimaculoides Registered

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    It says on the DI cartridges to run 4 gallons through them before using the water, and the first few gallons were indeed a dark color. These are 1/3 carbon 2/3 di filters, I have 2 in series after the RO unit.
    Since my ultimate goal is to keep a ceph in this tank, I'm trying to do all I can to rule out something dumb like water quality in case of death.
     
  5. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    I have not seen the combination filters (my post filters are separate and I had forgotten the additional carbon in the last stage on my unit) so it makes more sense now. The dark water would be from the carbon dust. I can vouch for using RO/DI water with or without octo as making a difference in my own tanks and have to agree with you decision to make your own clean water.

    As for the numbers, 7-8 is what I show on my TDS as well (34 going in). Thales has suggested that it should show 0 but the lowest I remember seeing was 5 (I am overdue to have to change the RO filter again). My in-line (great addition when you have about $35 in spare aquarium cash) meter is not supposed to have to be recalibrated and it matches the hand held.
     
  6. robind

    robind O. bimaculoides Registered

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    These postfilters are also separate, but I believe they have a 'mixed bed', though they are opaque so I can't say for sure.
    I also have an inline tds meter, very handy to have. However the probes are stainless steel, so I'm a bit worried that that might impart something to the water. If I rotate the probes on the tds meter, it changes the reading. I can make it read 2 when I do that, though it says in the manual they're supposed to be in a specific orientation, and in that position they read 7. I just think its weird that the DI filter is doing nothing, and in fact sometimes increasing the tds reading. Maybe I should switch the probes and see if one's faulty or something.
     
  7. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Increasing the TDS is the reason that DI was FDA rated as not potable for a long time (I believe that has changed now). What you are seeing is normal. There is now sand (at a higher price) that is not supposed to impart anything into the water but I don't know that it matters unless you are drinking it. My sand is in a clear container but my post carbon is sealed. I am not sure that the post carbon does anything (it shouldn't) unless the water sits for a long time (not the case as I use up the water almost as fast as I can make it between topping off 8 tanks and doing 5 gallon per tank water changes weekly).
    My in-line meter is a cheaper version and has a simple switch for in-coming and out-going but it has matched with my hand held every time I have double tested so I have learned to trust it. I have to run the unit to get a good out-going reading but the incoming is consistent (I prefilter the house water before the RO and STILL have tons of our lovely red mud). I would like to add an ultra violate to my system and have one I can use but the switch died and we have not taken the time to see if it can be fixed. If I ever find a job, it is on my shopping list. I see so much mud in the water (as well as traces of nitrate) I am never sure that the chlorine kills all the bacteria. In any case, none of my octos have died from water quality issues so I don't worry about the probes (changing out the brass was a good idea though since brass is partially copper).
     
  8. robind

    robind O. bimaculoides Registered

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    I think we have the same meter. I didn't know that about DI, I thought it was supposed to lower your tds beyond what the RO did. I guess the only way I can get a better reading is by running it through another RO membrane, which would likely require a booster pump. But it sounds like that is totally unnecessary. Is there another way I can get a lower tds reading? Does it matter?
    Tomorrow I'm going to start filling the tank, after I drain out the RO water that's in there. So now it'll be ro/di water. Probably will take a few days.
     
  9. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    My unscientific but researched understanding is that DI treatment (which DOES NOT MEAN DISTILLED as so may people think which requires heating and evaporating the water) is a chemical process that removes minerals and metals (called DeIonization). The end result should produce a water close to distilled water (some people do use distilled if RO/DI is not an option but RO/DI filtering was used by the emergency crew during the flooding in New Orleans to make drinking water). The sand bed that the water passes through causes a chemical reaction with the water and traps the minerals and metals (copper being the biggest concern for saltwater aquariums) and needs to be changed frequently. Needed salts and minerals are added to this dead water with your salt mix. With the older style and still available sands the single pass DI will often increase the TDS slightly but I have read that there are now single pass sands that put nothing back in the water (I refill my DI canister and don't remember if the last I bought was of this type :oops:)

    You can find debate about the drinkability of DI water but the companies selling DI units claim it is potable. This may or may not be the case for the single pass that we use to make tank water. An internet search will bring all kinds of conjecture but gleaning an answer is difficult. One thing is certain, it tastes flat. When I buy bottled water, I get RO/DI water with minerals added back for taste. RO water IS potable without debate.

    Nothing in the RO/DI process deals with bacteria which is why I am considering an ultra violate bath before the water goes into the tank (I run one on the reef but circumstantial evidence suggests it may have a negative effect if used on an octo tank) since mud means ground water and ground water means bacteria (the water supplier added chlorines are designed to handle this for human consumption but I trust less and less these days).
     
  10. robind

    robind O. bimaculoides Registered

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    OK, well I suppose I'll just go ahead and use it then. Right now the tds going into the di is 7, coming out it is 14. But I have all kinds of copper plumbing, so anything I can do to strip that out the better. How can I tell when my DI is spent? It's in an opaque canister, and it seems like the tds reading doesn't mean squat regarding the effectiveness of the DI.

    I'm reading posts on other forums of people saying that they get ro water at
     

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