Tommy January 30, 2019 Share January 30, 2019 Hey guys ! So I've been using the Mighty mite RODI (50gpd) system for my reef tank for the last few years and it seems that I can only get 0 TDS in the first 100g of water or so, after that the TDS starts to go up and I've been changing the all the filters every couple months or so, Is this normal? I've been thinking about getting a new RODI system and im wonder on a regular system, how many gallons of clean water can you get before you have to change out the filtering cartridges as the TDS starts to rise. Thanks Link to comment Share on other sites More sharing options...
smh254 January 30, 2019 Share January 30, 2019 That’s not normal. I have a 75gpd RODI unit and change the sediment filter, carbon filter and DI resin about every 1000g. The RO membrane about every 2500g. These numbers are all a guesstimate but I’ll go years without changing the RO membrane. It could be you have it hooked up wrong or maybe your TDS from your house is high. My house tds is 120. And I make about 25g of water a week. Can you take a pic of your unit?Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Jon Lazar January 31, 2019 Share January 31, 2019 2 hours ago, Tommy said: I've been thinking about getting a new RODI system Your results are not what most people experience, but it's still possible that the RODI is functioning normally given your tap water. You need to figure out what's going on with your current setup before you buy a new system, because you may need to buy an RODI that addresses your tap water issues (if there are any). Otherwise your new RODI could suffer from the same poor performance as your current one does. - Are you on a well? It's common for well water to have elevated CO2 levels which rapidly deplete your DI resin. - Does your tap water have high TDS? Your Mity Mite RO membrane is rated at 98% under ideal temperature (warm) and pressure (high), and the actual performance is probably less than that. Let's say your input TDS is 400 and your RO membrane is removing 96% of TDS. That means the water leaving the membrane and entering the DI filter has a TDS of 16, which will also rapidly deplete your DI resin. - Does your water utility use chloramine? In Fairfax we use chloramine half the year. Chloramine will damage the RO membrane, reducing your TDS performance, and increasing your DI usage. I would start by taking TDS samples of your input water and RO (not DI) output water. Measure your water pressure going into the unit. Also check with your water municipality and see whether they use chloramine. They probably have a complete water quality report available online. Link to comment Share on other sites More sharing options...
Origami January 31, 2019 Share January 31, 2019 The Mighty Might is a small, modular RO/DI system with sealed, inline stages and sold by AWI. It has a 50 GPD membrane with a 98% rejection rate (under ideal conditions), prefilters and a sealed mixed bed DI stage with a 3,380 ppm-gal capacity. Assuming that you're exhausting the anion and cation resins at the same rate (in other words, your water after the RO membrane has roughly equal parts positively and negatively charged ions), then you should be able to process somewhere between 350 and 1000 gallons (most likely) for water from 10 down to 3.5ppm after the RO membrane. (3.5 x 1000 = 3500, and 10 x 350 = 3500; both ~ 3,380 which is the capacity of the resin per the label.) The expected lifetime is higher if the TDS out of the membrane is less, though. That's conditional, though, on several factors. 1) If your RO membrane is worn or extremely inefficient now, then your TDS out of this stage will be less. 2) If you're making RO/DI water in only very small bursts, you'll get a TDS burst out of the membrane which will exhaust your resin more quickly. Making water in larger amounts at each sitting will stretch your DI resin. 3) If the ionic content of the RO water is skewed (unbalanced), then one resin component may exhaust faster than the others. (See below.) Users on well water may be challenged by #3 above if their water comes out of the ground with high dissolved CO2 (which dissolves to form HCO3- and CO3--). These ions, called anions because they are negative and attracted to a positive anode, are small and get through the RO membrane and into the RO water stream and more quickly deplete the anion resin because the resin is trading out its negatively charged OH- ion for the negatively charged HCO3- ion (or 2 OH- ions for one CO3-- ion). This may not apply to you as you may not be on a well. So, is the early depletion normal? No. Will a full-up RO/DI system help? Maybe, especially if it has either an autoflush or manual flush that you trigger before producing new RODI water. But, since the most common DI resin stage for our larger systems have a capacity of around 8000 ppm-gals, you'd only get about 2 to 2.5x more than what you're seeing today if whatever is going on now is not corrected. Link to comment Share on other sites More sharing options...
ImGoingCoastal January 31, 2019 Share January 31, 2019 I had a somewhat similar issue with an aquatic life unit (similar to the mighty mite, which I owned several years ago). My color changing resin was depleting/changing color waaaayyyy faster than I imagined. It was halfway "depleted" and I've ran less than ~200 gallons through it at ~30 gallons at a time.I was wondering if there is such a thing as too much water pressure? My waste water was flowing like a pressure washer.-A-a-ron Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 So... My friend is out of the hobby and giving me his full-size RODI system, I think it will be much better than what I have. Went to test the Mighty Mite earlier and according to the inline TDS meter the "Out" water was at 59 and the "In" water was at around 40 and slowly declining...Very slowly...around 1 point per minute. There's a chance that I may installed the filter cartridges the wrong way, I'm not 100% sure because what I did was looking at stock photos of the unit and based on that for the installation. But then, If I did it wrong how come the TDS always at zero on the first 100g or so? Thanks Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 So... My friend is out of the hobby and giving me his full-size RODI system, I think it will be much better than what I have. Went to test the Mighty Mite earlier and according to the inline TDS meter the "Out" water was at 59 and the "In" water was at around 40 and slowly declining...Very slowly...around 1 point per minute. There's a chance that I may installed the filter cartridges the wrong way, I'm not 100% sure because what I did was looking at stock photos of the unit and based on that for the installation. But then, If I did it wrong how come the TDS always at zero on the first 100g or so? Thanks Link to comment Share on other sites More sharing options...
Origami January 31, 2019 Share January 31, 2019 @Tommy , the RO water output on the housing is normally the more centrally-located line coming out. Your pictures shows this is connected up properly. If the RO membrane is not seated correctly in the housing, you can get high TDS numbers out. I don't see the TDS in and out points in your picture, so I can't comment specifically. However, the numbers that you show for either are high if they're numbers that are after the RO stage. (I don't see any inline testeter, though, between the RO membrane and the DI stage in your picture above.) TDS is zero for the first 100 gallons because your DI resin is acting like a sponge and sucking up the dissolved ions. Once this "sponge" is full (i.e. depleted), it starts releasing ions back into the water and TDS starts to rise. @ImGoingCoastal Aaron, typical waste:pure ratios for RO/DI systems is 4:1 to 6:1 - typical. There's supposed to be a flow restrictor present on the waste side of the line coming out of the housing. This allows sufficient pressure to exist across the membrane to drive "pure" water through the membrane to the "pure" water output (the central line going to the DI stage). If you're getting high flow out of the waste line and little to no flow out of the pure line, you could be missing a restrictor. If the membrane is plugged or has been left to sit after use without regular use, effectively drying up, then it will not pass much water and most of the flow will be through the waste side. Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 So...After talking to my reefing buddy BK_Market for a while, we came to realized that the flush valve was "Open" for the last 2-3 years or so, he said basically I was reefing with tap water the whole time. I didn't know that it was supposed to be closed all the time. I think this explains my Bryospis and GHA problem that I've been dealing with for years. I feel so stupid and careless but I'm excited that better reefing days are ahead. Link to comment Share on other sites More sharing options...
ImGoingCoastal January 31, 2019 Share January 31, 2019 ....I don't think mighty mites have a flush valve?....I have some bryopsis in my fairly newly established tank. I don't know what to do about it.-A-a-ron Link to comment Share on other sites More sharing options...
ImGoingCoastal January 31, 2019 Share January 31, 2019 I retract my previous... I thinkPer their website it has a "fast flush flow restrictor".-A-a-ron Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 Yea man, its a little blue valve, its the only valve on the system. Bryospis is prolly the hardest algae to get rid off, I've been scrubbing the rocks in peroxide and saltwater mix and it seems to controlled it but theres always new spots. I'll let you know if its gone for good in a couple weeks since I just scrubbed it a couple days ago. Link to comment Share on other sites More sharing options...
Origami January 31, 2019 Share January 31, 2019 The flush valve basically bypasses the flow restrictor, leaving very little pressure across the membrane to drive water across. It would lead to very low production and, quite possibly, severely reduced efficiency. Think of a flow restrictor this way: Imagine that you're trying to separate sand from some sand-containing water. And, to do this you've set up a system to pump some that contaminated water up through a vertical pipe pipe with a (drain) hole in the pipe part way up. If the hole's too big, then all the water and the sand flow out of the hole. If the hole's completely closed, then all the sand and water flow out the top. But, if you restrict that hole in the pipe some, then the heavier sand and some of the water flow out of the drain and clean water rises up through the top of the pipe. That's analogous to how your RO membrane works inasmuch as the restrictor on that drain (or waste) hole is sized to let the dissolved solids wash out but still leave enough pressure to drive the clean water out through the top (i.e. the pure water output). If the flow restrictor is in bypass mode, then you've basically routed most all of your water to the drain. leaving with very little getting past the membrane and making the membrane highly inefficient. That results in faster depletion of the DI resin. Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 Thank you Tom! Picked my friend's RODI system this morning and everything is good, TDS is at zero at the moment, this one doesn't have the flush valve. I think its a 4stage Omnipure system. Its making water 2 times slower than the one I have before. With the old one it was supposed to be 50gpd but I was making 5g at about 45 minutes so that should have been the red flag right then and there. This one is making it at a 5g every 2 hrs and its a higher output system. Link to comment Share on other sites More sharing options...
madweazl January 31, 2019 Share January 31, 2019 You can also pick up a cheap hand held TDS meter from the likes of Amazon for $15 that will give you a good idea of what your tap TDS is. Ours is around 100 (Stafford water) and I get 2 after the RO membrane (BRS 4-stage). Handy for checking the condition of your RO membrane. Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 Thank you, I have a hand held one as well as an in-line TDS meter for my RODI. Link to comment Share on other sites More sharing options...
Origami January 31, 2019 Share January 31, 2019 13 hours ago, Tommy said: Yea man, its a little blue valve, its the only valve on the system. Bryospis is prolly the hardest algae to get rid off, I've been scrubbing the rocks in peroxide and saltwater mix and it seems to controlled it but theres always new spots. I'll let you know if its gone for good in a couple weeks since I just scrubbed it a couple days ago. Tommy, I can't see the valve, but I see what may be some sort of flow restrictor under that sediment filter on the bottom of the filter stack in your picture. I can see the waste line coming off of the RO housing and see it taking a slight dip as it goes behind the sediment filter. It then emerges below and feeds into what would logically be a flow restrictor. This would be the device that had the valve on it (or there would be some way of routing around the flow restrictor - that's all a fast flush valve really does, it just routes around the restrictor). Can you post a picture of the valves and the restrictor from the other side of the setup? 1 hour ago, Tommy said: Thank you Tom! Picked my friend's RODI system this morning and everything is good, TDS is at zero at the moment, this one doesn't have the flush valve. I think its a 4stage Omnipure system. Its making water 2 times slower than the one I have before. With the old one it was supposed to be 50gpd but I was making 5g at about 45 minutes so that should have been the red flag right then and there. This one is making it at a 5g every 2 hrs and its a higher output system. 5 gallons in 45 minutes (160 gpd) for a 50 gpd unit does not sound like a situation where a flow restrictor valve was open. It sounds more like the RO membrane was not fully seated in the housing or was blown. (It could also be that the flow restrictor was clogged, too.) Either way, the "pure water" output would be high in TDS, resulting in fast resin exhaustion. If a flow restrictor (bypass) valve is open, it drops pressure across the membrane to near zero, which results in very little water getting through the membrane. Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 I would post pictures of the valve but I just now seeing this. After installing the new system and running around getting replacement membranes for it, I threw the Mighty Mites in the trash because it was also leaking water every time I turn it on. I saved a few elbows and clips for future usage. Link to comment Share on other sites More sharing options...
Origami January 31, 2019 Share January 31, 2019 Always good to have a few spare parts. Link to comment Share on other sites More sharing options...
Tommy January 31, 2019 Author Share January 31, 2019 Yes Tom ! Thank you so much for your input on this matter. Link to comment Share on other sites More sharing options...
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