Pies Posted April 29, 2003 Report Share Posted April 29, 2003 Heya. I am in Wellington and am looking for a RO/DI unit. I've rund a few water purfirer places and can get a 3 stage RO unit for about $500. DI on top of that. Now all I know is I need pre filters and a membrane .5 microns. If you know anything about RO and know where I can get one cheaper please contact me. I don't want it plumbed into the house/kitchen, just onto a lead I can attach to the washing machine taps or something like that. Its for freshwater (Kalkwasser) topup in my Marine aquairum. Cheers Pies Quote Link to comment Share on other sites More sharing options...
ajbroome Posted April 29, 2003 Report Share Posted April 29, 2003 Pies said... > Its for freshwater (Kalkwasser) topup in my Marine aquairum. You could probably use clean rainwater. Or else, if you're ever in Palmerston North I could easily supply you with 20L or so of RO water at a time... I'm sure units are available cheaper than that. I seem to remember Trevor Sartorelli in Upper Hutt making RO water and I'm sure he didn't pay that. Presumably you've talked to people like: http://www.purewater.co.nz/index.htm and http://www.wellingtonwaterfilters.co.nz not that they're cheap but they may know of used units available... Andrew. Quote Link to comment Share on other sites More sharing options...
Caryl Posted April 30, 2003 Report Share Posted April 30, 2003 You are coming to conference aren't you pies? Talk to Warren Stilwell while you are there as I believe he is a veritible mine of information re RO. Andrew will be there too of course Quote Link to comment Share on other sites More sharing options...
ajbroome Posted April 30, 2003 Report Share Posted April 30, 2003 Caryl said... > Andrew will be there too of course It's true, I will. Tickets are booked and paperwork is in the mail... Looking forward to it. Andrew. Quote Link to comment Share on other sites More sharing options...
Caryl Posted April 30, 2003 Report Share Posted April 30, 2003 "Paperwork is in the mail" Now where have I heard THAT before?? :lol: Quote Link to comment Share on other sites More sharing options...
Pies Posted April 30, 2003 Author Report Share Posted April 30, 2003 Yes I will be at 'conference'. I have approx 15 ltrs of RO water left. Using about 2.5ltr a day (evaporation). I may fix some temp lids to the tank and sump to reduce water evap but would rater not. Ajbroome: Thanks very much for your offer. Don't suppose you could make me up 100+ ltrs? :> I will call those numbers you gave me, thanks for that! I rung a few places and couldn't fund anything for less than $500 and thats without a DI unit (I would like RO/DI). Hopefully someone will have something cheaper. I would need less than 5L per day so doesn;t need to be a massive unit at all. Most units seem to be the 'under the sink' varity. Maybee there is a less 'consumer friendly' product about? You are also right about rain water, although it still needs to go through a DI unit. But I think i would prefur the stability and consistancy of the RO/DI soultion. Thanks for your offer, and if you can make me 100ltr + I would come to PN this weekend to pick up (I have 180ltrs of jerry cans!) help! Pies Quote Link to comment Share on other sites More sharing options...
Warren Posted April 30, 2003 Report Share Posted April 30, 2003 Natures Sunshine Products make a RO unit that easily plumbs onto a tap. It produces about 80L of purified water a day. RO units aren't meant to be turned on and off but if you use it every day it should be ok as the water will not go stale in that time (this particular unit seems to have been designed for intermittent use). It would take about 45 mins a day (depending on the water pressure) to get 2.5L. The unit used to retail for about $250.00. I have 4 of these units permanently plumbed in outside feeding 2000L storage drums. After adding stabilising salts I use the water for all my water changes. The quality of these units is such that you should not need a DI after it. The basic unit will be good enough for all you want. One of these units is good for about 80000L of purified water if you replace the pre and post filters with bigger commercial ones. For your situation however, I'd expect you would get years of use from it with the amount of water you require. You would also be able to use the standard filters supplied with the unit. W. Quote Link to comment Share on other sites More sharing options...
ajbroome Posted April 30, 2003 Report Share Posted April 30, 2003 Pies said... > ... if you can make me 100ltr + I would come to PN this > weekend to pick up If you really need it, I can organise it. Contact me at [email protected] and we'll see what we can sort out. Andrew. Quote Link to comment Share on other sites More sharing options...
Pauly Posted May 1, 2003 Report Share Posted May 1, 2003 Hey pardon my ignorance but , can some one please explain this ro/di stuff too me . Cheers , Paul . Quote Link to comment Share on other sites More sharing options...
ajbroome Posted May 1, 2003 Report Share Posted May 1, 2003 Paul said... > ... can some one please explain this ro/di stuff too me . It's purified water. For some applications people want as close to H2O as possible with a minimum of other chemicals dissolved in it. Tap water generally has a whole host of chemicals included, most of which are perfectly fine for 99% of aquarium applications. However, sometimes people want/need 'cleaner' water, marine reef tanks can be one of these applications. RO = Reverse Osmosis, water is 'pushed' through a membrane that excludes many of the bigger dissolved ions. Typically you get a small percentage of RO water and a large percentage of 'waste' water that has slightly more mineral content than the starting (tap) water, hopefully people use this to water the garden or some other purpose rather than just letting it go down the drain... DI = De-Ionised, where RO water has even more (usually smaller) ions removed as well. This is *very* clean water, prone to wild fluctuations in pH and causing osmotic damage to fish cells if used as it comes out of the machine. Generally people add the salts they want to the pure water to obtain some specific chemical characteristic they want. As I said, for almost all typical aquarium applications it's not necessary to use such pure water and in some cases even rain water will work as well. There's some info here: http://www.thetropicaltank.co.uk/purewatr.htm Andrew. Quote Link to comment Share on other sites More sharing options...
Midas Posted May 2, 2003 Report Share Posted May 2, 2003 What about those 'tap water purifiers' some pet shops sell that are based on ion-exchange? These give de-ionised water too. They have cylindrical cartrigdes with a small section of carbon and ion-exchange resin. The water flows through the bottom of the cartrigde past the carbon and then fluidises the ion-exchange beads, with the de-ionised water coming out the top. I had one of these but ended up selling it not long ago for $40 as it was surplus to my requirements. Cost me about $100 new on special, but I think they are normally around $150. It used to take about 1/2 and hour to fill a 10 litre bucket, so doesn't sound too bad compared to the alternatives you are currently looking at with RO. I think they are marketed by Aquarium Pharmaceuticals, I've seen them in several pet shops since I brought mine. New cartriges cost around $30 and I'm not sure excatly how long they each would last, but I used one for about six months on and off and it was still working ok by the end of it. Longetivity I guess would depend on how many ions were in the tap water to start with. Quote Link to comment Share on other sites More sharing options...
Warren Posted May 2, 2003 Report Share Posted May 2, 2003 The AP Tap Water Purifier does work very well but is also just about the most expensive way to purify water. I purchased one once. It produced about 200L of water before the resin was exhausted. It is specially designed so that the anion and cation resins are mixed together. If they weren't you could easily regenerate them for re-use. Whats worse is I'd emptied 50% of my tank (500L) so once the filter was all used up I had to put 300L in from the tap. So I wasted what little the filter had done anyway!! $150 down the drain (literally). Others may get more than 200L from this purifier depending on the tap-water quality. A much better alternative is RO. The water is just as good if not better. You will get approx 80000L from one membrane before it gets blocked up. A new membrane is about $140. So $150 or so to get 200L using DI or $140 to get 80000L using RO, hmmm... I wonder which one to buy... :-? Its not quite as good as it sounds as the RO needs extra filter cartridges as well. It still works out that you get about 200x as much water from RO for the same price as DI. The example above shows 400x as much, but you'll need about $140 of filter cartridges per membrane throughout its life. I get about 1.5 years out of a membrane running 24/7 and producing approx 500L / week. I'm currently using 2 membranes full time so get approx 1000L/week. It all gets used up in water changes. 8) Quote Link to comment Share on other sites More sharing options...
Ira Posted May 2, 2003 Report Share Posted May 2, 2003 I've also seen ads for pumps that are powered by the flow of the water(Not sure how that works) that increase the water pressure so the ratio of waste to RO water gets up to about 50%, if you're worried about wasting water. Quote Link to comment Share on other sites More sharing options...
Midas Posted May 5, 2003 Report Share Posted May 5, 2003 To be fair the AP tap water purifier comes with 2 cartridges, therefore would give 400L of water for the initial $150 outlay. Although I got significantly more litres than this from my cartridge and it was still going strong, however the tap water being de-ionised was quite soft at around 40-50 ppm CaCO3. New cartridges are $30, so each additional 200L would only cost $30 not $150. However Warren is right, if you are using a decent amount of water you would be better off going with RO as the initial extra capital outlay of buying the RO would soon be surpassed by buying additional ion exchange cartridges. Using 2.5L/day it would only take approx 1.5-2 years for the cost of replacement cartridges to outstrip the extra initial outlay of buying the RO. Here's an idea: If you were to buy the AP tap water purifier you could use both cartridges supplied then throw away the old resin (as the beads are mixed as mentioned by Warren and can't be recharged) and carbon insides when spent. Then get some new carbon and source some new anion and cation resin beads (seperately). One of the spent cartridges could then be filled with anion exchange resin and the other with cation and the two units placed in series to filter the water. Then the two resins would be kept seperate and could be recharged as often as you like when spent, with the only expense being the chemicals required to recharge the resins. What do you reckon Warren? Wouldn't be too bad if you were dealing with small quantities of water required. Quote Link to comment Share on other sites More sharing options...
Warren Posted May 5, 2003 Report Share Posted May 5, 2003 Yeah, good idea. You also seem to have found a much cheaper source for the cartridges. It was at least 6 years ago when I got one. Then it only came with one cartridge and replacement cartridges cost nearly as much as the original unit. I guess pressure from alternative purification methods has pushed the price down. RO is relatively compeditively priced now considering how much extra water you get per $. If you can find a reasonably priced source for the anion and cation beads it wouldn't be a bad idea. You could even set it up from scratch if you can find 3 suitable containers to start with. The recharging solution is also very cheap, from memory I think one is some kind of salt (or maybe both). You can pick up most salts really cheap ($20 for 25kg) and this amount would last many recharge cycles. RO may still be the way to go. It is much lower maintenance and no recharging is required. You just replace cartridges and membranes when they are shot. RO will normally go for 6 months 24/7 without any maintenance. Quote Link to comment Share on other sites More sharing options...
Pies Posted May 5, 2003 Author Report Share Posted May 5, 2003 Thanks for all the good info! Warren you are right, DI is VERY expensive and 200L for 1 2L cartridge sounds spot on. I rung around and most places said you would get 225ltrs of DI water from 2L of resin based on the Auckland water suply. The cheapest place I could find a DI unit was Vivendi in Auckalnd. $139.00 including fittings for taps etc. 2L of resin (refil) is $75.00. I have ordered one. RO. I have opted for an RO unit from WATERS here in Wellington. They have made me a 3 stage (5 micron pre filter, carbon filter & .5 micron RO membrane) all plumbed up and ready to go for $360.00. Most people for reef tanks use DI water and use the RO to get a better economy out of the DI. By using the RO to mostly filter the water, and the DI to get the rest. This way you get water over 99.5% (so I read on reefcentral.com) pure. So thats me! And thats why Cheers all! Quote Link to comment Share on other sites More sharing options...
Warren Posted May 6, 2003 Report Share Posted May 6, 2003 Hi Pies, a good RO should get 99.5% - 99.9% all by itself depending on whats in the water to start with. I've also never heard of an RO having a micron rating. The membrane works at a molecular level and wouldn't have a micron rating (if it did, it should be a nanometer rating anyway). Best check they are making a true RO and not something else. I use TFC membranes as we have no chlorine in our water. You may need a CTA membrane in your area to effectively remove the chlorine. What is your iron level like in the water supply. CTA's don't like too much iron. Quote Link to comment Share on other sites More sharing options...
Pies Posted May 11, 2003 Author Report Share Posted May 11, 2003 This unit has an RTC membrane. It sounds like a failry 'common' unit for here in Wellington. So its just a case of wait and see I guess? It is up and running now and ive been using it for about 5 days. I read somewhere about the micron rating of the membrane but I think you are right, there is no mention of it on mine, but the pre filter has a 5 micron rating. My DI should arrive this week and I will mount it all in the spare toilet in my garage. Cheers! Quote Link to comment Share on other sites More sharing options...
Warren Posted May 12, 2003 Report Share Posted May 12, 2003 Hi Pies, I've never heard of the RTC type. I even searched the net to check and couldn't find anything. Are you sure its not some kind of ceramic filter. I did find some reference to RTC as ceramic filters that remove radioactive particles from water. I'd expect you wouldn't need to worry too much about that however. What brand / type is the membrane? W. Quote Link to comment Share on other sites More sharing options...
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