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melev

I love this time of year

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by
melev
, 10-26-2014 at 07:20 PM (7981 Views)
It's around this time of year that I watch the TDS of my RO unit drop. I'm talking about the output of the RO system before the DI stage.

Whenever I turn on the RO/DI system, which is twice a week, I open a valve before the DI stage and let it run for 90 seconds. By avoiding TDS creep, DI resin lasts longer. Link: http://www.reefaddicts.com/content.p...thy-of-concern

Once the water is flowing, I'll turn on the TDS meter to observe the numbers rise and fall. During that first minute, I'll watch the number ascend to nearly 200 and rapidly drop back down to the normal operating reading. Over the past seven months, it's been around 23 coming out of the RO membrane but as we head toward winter, that number drops. Today, it's coming out at 10. The benefit of the lower TDS is that the DI resin will last longer, and who wouldn't like that?! Last winter I saw the TDS drop to 6 before the DI stage, so that cartridge lasted a good long time polishing the last of the TDS to zero. Why the change? The city is no longer adding stuff to the drinking water during the cooler months, basically.

In other news, my Tiger Cowrie came right out into the open yesterday for a photo op. Link: http://melevsreef.com/blog/tiger-cow...ghted-10252014

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Categories
‎ Tank Entry , ‎ Water Chemistry

Comments

  1. gettareef's Avatar
    That's a very large, and very pretty, tiger cowrie. I really love the look of these interesting creatures; think I may get one (most likely some smaller ones as I only have a 75 gallon).

    When you say you let the water run for 90 seconds or so after the membrane, isn't this the same as using the flush valve? I didn't have one installed for the first year when I began my reef and DI resin exhausted so quickly. Flush valves are definitely a money saver. I also like to watch the TDS meter when running the flush valve, and when running, all year round no matter what time, the TDS seems to not increase at all but starts around 25-50 and will decrease to about 6-10 after roughly 3 minutes. That is the que to turn the flush off and DI on. Oddly though, it seems like the longer I'm making water, I'll check the TDS output off the membrane and it will have actually decreased from 6-10 to 1-5. Less work for the DI I guess. I take it that the lower TDS after the membrane for me compared to you has something to do with our cities various water treatment methods/chemicles.

    On another note, I plan to email you soon Marc to get some ideas and price quotes on building a custom sump for my system. Keep checking your inbox!
  2. melev's Avatar
    Membranes are more efficient during long runs, which is why I recommend running it once a week instead of daily collection. My reef's top off reservoir is big enough to last over a week, but I also collect drinking water to a bladder tank under the sink that stores 3g of water. That amount is used for making coffee, tea, drinking water on-demand, and the fridge's icemaker. Link: http://www.reefaddicts.com/entry.php...my-RO-DI-setup I tend to use that up quickly, so the RO system is turned on twice a week.

    For a common week starting on Sunday, this is the process:

    Turn on RO system and bleed off water before the DI stage into the washing machine for 90 seconds. Check the TDS via the meter - all is well - close the bleed valve and open up the valve that feeds the bladder tank under the sink. Once full (15-20 minutes), close the valve. Then close the valve on the red line going into the RO system just as a precaution even though the system is off, silent, and fully pressurized. I used to only do this for trips, but now I just do it every time. The idea is limiting the risk that something could let go and shoot water everywhere, although this has NEVER happened.

    On Thursday (about 3-4 days later), repeat as above to refill the bladder tank. I know it is low because the water coming out of the spigot on the sink will be quite a bit slower. Once the bladder tank is full, I'll close that feed's valve and open the valve that refills the ATO reservoir under the reef. This takes 3 hours or so, and this is when the DI resin is being used. Since I had the RO system running to the bladder tank first, the membrane is 'warming up' so to speak. The TDS is low since it is have been running for a duration, and the DI resin lasts better for me that way. When the container under the tank is full, the float valve rises up and pinches off the line. I'll hear the RO/DI system shudder to life every 20 seconds, an audio reminder to go turn it off. Since I'm in the general area this works out nicely. I'll close the ball valve feeding to the fish ATO reservoir, and then again the ball valve feeding the RO system. This method has been my routine since early 2011.

    If you watched the video in the TDS Creep article, you'll see how quickly it rises and falls. This is how I've always done it and it makes sense. A flush valve bypasses the flow restrictor in the waste line. It should only be opened 15 seconds, the closed - the idea is to wash away the water sitting around the membrane. I'm not sure why you are observing the readings you are with that method you described because in theory no water would be coming out of the product line because the flow restrictor isn't applying back pressure on the membrane. Maybe you should try my system instead. I put a link in the top of this post showing how it is all plumbed together, but I can always add more pictures or maybe do another video.