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nitrate think tank I'm at my wits end


pizzaguy

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I was pretty speechless. She was basically telling me to buy Di resin in bigger bulk so I'm not ordering it as often. The moral of the story is this. Something is wrong with my unit no way around that. I know plenty of people with the same one and it's nothing like mine. Thing is there all pretty basic so I'm not sure what could be wrong. I am going to replace every filter including the membrane and see what happens.

I've never read on here anyone having this problem so clearly something is wrong.

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Yeah that is so wrong.

 

I have already made 300 gallons of water on a new resin cartridge and it hasn't even started to turn color or look used. 

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Are you on the TIII? I have used my unit for well over a year, just replaced the filters in January, and I have NO idea what my TDS is before going in, but coming out I can assure you it's 0. I change 50 gallons of water every two weeks, and I top off 5 gallons every 4 days or so.

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Yep same one. But mines working right as she says. Everyone's getting 1,000 gallons plus except me. Sorry to rant but it's pretty irritating.

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Something's wrong with the unit, Has to be. Maybe the ro filter has a defect. Can you take all the filters out and read the tds stage by stage as you put the filters back in? You should see a big difference in tds once you make it to your ro filter

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Wow, just read through the whole thread. Interesting problem you're having.

 

I use the mighty mite rodi unit, have been for about 8 months now, it's supposed to make only 50g per day and I'd bet I've made over 1000g with it. My tap water tests at ~150-200 tds depending on the day and it's still reading at 2 coming out of ro and 0 coming out of di all the time.

I'm not an expert on denitrification, but I can say that I don't have problems growing chaeto with slow flow through my fuge and a $30 daylight par38 bulb from lowe's. Everything is growing in there. I have chaeto, caulerpa and now a mangrove all tied up and I'd say I double the chaeto/caulerpa once a week. So about a soccer ball size clump every week. Granted I don't even know what my nitrate/phosphate readings are, but everything else is growing and happy.

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By the way awi said I should only be getting 100 gallons out of my Di resin. That's normal.

Normally, you can get way more out of your resin. But it really depends on what's coming out of the RO membrane.

 

DI resin can be exhausted very, very quickly if you have high CO2 in your water. This is not uncommon in situations where you're on a well. CO2 rejection rates through most RO membranes is practically non-existent. That is, the membranes pass the CO2 almost without any filtration whatsoever. The loss of buffering in the water and the high CO2 results in a pretty acidic effluent coming out of the membrane stage. For example, both DaveS and I have this issue. I think that Dave installed a front-end in his water processing for his house to explicitly reduce CO2. I've yet to take that step. Other people have used an intermediate storage container that they bubble fresh air through to de-gas the water before pumping it through a DI stage.

 

Here's a resource.

 

Try googling "co2 ro membrane di resin" and see some of the hits.

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I'm on cit water if that means anything.

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City

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Still, Eric, while it mostly affects users on well, if you have high CO2, it could be the reason behind your rapidly depleting DI resin. I used to run six months on a DI cartridge in Ashburn where I was using upwards of 50 gallons of week of RO/DI water. I probably can't get 150 gallons out of my cartridge today at home on our well water without additional processing.

 

Take a look at the links and see if the tests / calculator there provides any additional insight into your DI resin problems.

 

What's the TDS of the RO water coming out of your membrane (pre-DI resin) now?

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I'll check when I get home this evening but I guess what gets me is I never had this problem with the other 2 units at the same house in the same spot and tds from tap has always been the same. But I will check for sure.

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AWI is a sponsor here and has a forum here.  Is there some way to get some clarification of why the phone support would tell someone that they need new DI resin every 100 gallons?  It just makes no sense to me unless he's running raw sewage through the thing instead of tap water.

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I'll check when I get home this evening but I guess what gets me is I never had this problem with the other 2 units at the same house in the same spot and tds from tap has always been the same. But I will check for sure.

That's significant. I didn't know that. I may not have read it earlier.

 

Several things worth checking:

 

a) Check to make sure that your RO membrane is seated well in the housing. This will require you to open the housing (water will spill out, so keep a towel or a tray under it), and try to pull the membrane out. If it comes out easily, it was not seated well and water was bypassing the membrane. While you've got the membrane out, note the part number on the membrane so we can make sure that it's the right part.

 

b) Check the TDS on the output side of the membrane after it's been running for several minutes. There's a TDS spike at the beginning of operation for most systems, but this typically falls off after a few minutes. You should see about a 98% rejection ratio for the membrane. That is, if you have a 300 ppm water coming in, you should see about 6 ppm (or less) coming out of the membrane.

 

c) Check the flow restrictor value and make sure that it's matched to the membrane output.

 

d) Check your input pressure. It should be somewhere between 50 and 75 psi.

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Quick update nitrates steady climbing. Approximately 30 to 35 now withing a few days. Tom, thanks for all the rodi suggestions. Gonna be tommorow before I get those aaccomplished kids are keeping me busy tonight.

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Thank you jason I'll keep that as an option if the others don't work. Quick update as to what's been happening. Will try to keep it short

Started dosing po4 9 days ago as nitrates were just steady climbing. dosing only 1 ml a day but it's highly concentrated. Nitrates are still climbing but not nearly as fast as they typically have. Tested on day 7 and finally detected some po4 on hanna. .10 po4. did not dose on day 8 so we didn't go overboard and re tested on day 9 and po4 was back to 0. So today is day 10 and dosed 1 ml again. Will test daily but it appears that the po4 is being consumed rather quick. Hopefully if it goes as planned the chaeto and biopellets will soon jumpstart and start working on the nitrates. Haven't changed any water in a few weeks. Trying not to unless absolutely necessary. Lost a few sps colonies and probably 70% browned out. Good news almost everything is colored back up quickly and polyp extension is better today then it's been in a long time.

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Wanted to thank jaddc especially for taking the time to help me and walk me through this step by step. He has been a tremendous help and continues to do so.

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Very cool to see some progress!

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So you think dosing the phosphate is lowering nitrate? I was dubious, but that's really cool if it's working.

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Nitrates are not dropping yet but there not climbing as quick as they have in the past. There's a lot of things out of balance like chaeto not growing or dying, bio pellets not doing anything. Hopefully the dosing kick starts these things to help start lowering nitrates.

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It is a food grade phosphate powder. I'm dosing 1 ml a day. There's a link a few pages back on what was recommended to use.

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I can't explain it but I can tell you my corals are thoroughly enjoying it! Haha

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