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Thread: RO Water Question

  1. #1
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    Question RO Water Question

    Currently I have a 65 gallon Discus tank that has been running now successfully for roughly 2 months with 6 Discus currently in the 4-5" size range. They are active and growing so I believe all is well here knock on wood!! I also believe in the "if it ain't broke don't fix it" philosophy, but I have been experiencing problems from the beginning with Nitrites (2-3 ppm) in my tap water that also contains chloramines. I add a water conditioner and PH buffer to the water (to get a PH 7.3 KH 50 GH 180) and run a sponge filter for 24 hours to get rid of the Nitrites before doing water changes but this whole process with the sponge filter limits my current daily water changes to about 20-25 (30% of tank volume) gallons every 24 hours.

    I also have a 100 Gal/day RO setup that I have not used at this point because I am confused about a few things that I hope someone can help me with as follows:

    After RO processing the water I plan to use Kent Marine RO right powder to re-establish the normal parameters but is a PH buffer also required to be added here in addition so a PH crash doesn't happen? After reading the directions on the RO right container I am very confused since it mentions the addition of PH buffers as well. Can someone help me here? I don't want to do something that would upset what is currently working with limits...
    Thanks in advance!

  2. #2
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    Default Re: RO Water Question

    Your nitrite level has nothing to do with water quality. Going to an R/O setup will not fix the problem. Nitrite is only present when the tank is not fully cycled. I offer cycled sponge filters to hobbyists in my area for free. Maybe there's something in your local fish club that would offer you one. If you're getting nitrite readings in your tap water, I recommend taking a sample to a fish store for reanalysis. I suspect these are not accurate readings.

    Frankly, many people starting out get caught up in water chemistry. You say you have 4-5" discus doing well for 2 months in the tank. Why are you trying to change things? Don't worry about water chemistry. Just keep up with water changes. Nothing comes close to having clean water for producing big, healthy discus.

    Good luck, Willie
    Why don't I read Harry Potter novels? Because I'm an adult.

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    Default Re: RO Water Question

    Hi Willie,
    My problem is I definitely have 2-3 ppm Nitrites in my tap water, not in the tank I have verified it with different test kits and after 24 hours with an active sponge filter in a trash can it tests 0 Nitrites with the same methods. I have tested it every 4 hours to see what was happening over time and can clearly see the numbers gradually improving to 0. I have also talked to the water company and they claim all their tanks are <1. The real issue is this is reducing the quantity of water I can have ready for daily water changes with my limited space to store and heat water.

    I don't know your feelings about water changes, but I have been doing 30% about 5 days per week and it has been working. That's why I was investigating the RO route as I thought I could double my production and possibly make it simpler.

    Thanks Wayne

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    Default Re: RO Water Question

    Hi Wayne;

    I've heard of one other report of nitrite in the tap water. The nature of biological filtration is, however, that nitrite is converted to nitrate extremely rapidly. If your tank continues to have nitrite, say 24 hours after a water change, then your filter is not fully cycled.

    I've had to rely R/O back in the day when the city dug up and replaced the water main in front of my house. They then added lime to seal the pipe. For 5 years, my fish lived in 100% R/O. They grew and spawned without my spending $0.01 on R/O Right. I'm still in the same house, but have changed back to straight tap. The water gets aerated and warmed for 24 hours, then it goes into my tank, 100% everyday.

    Playing with water chemistry is liking playing with matches. Lots of downsides, but no real upside. There's nothing to suggest that there's anything wrong with your water for raising discus, so I don't see any upside to messing with R/O.

    Keep up the water changes and enjoy your fish, Willie
    Why don't I read Harry Potter novels? Because I'm an adult.

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    Default Re: RO Water Question

    So my read is you want to know how you can increase your total volume without risking Nitrite toxicity which is present 2-3 ppm in your tap water?
    You can process ~ 25 gallons in a storage tank every 24 hours but have no additional space. I do agree that simplest is best and question what your values would be without the ph buffer you are using now...what are you fixing? What do you mean by conditioner? That can be an ambiguous term.
    Two options that I see:
    If you are adamant that you do not want to add even one drop of nitrites, then pull 50 gallons at night, add the 25 from your storage tank and another 25 overnight from your RO system without worrying about buffers or RO right. Sufficient required electrolytes should be in the seasoned tap water. Then check your kH and see what that is. too low and you risk pH crash. your value 50 is right on the edge of too low. I would expect a degrees kH to be between 3-6 (54-108 PPM)
    Alternately just add 25 seasoned 0 nitrite gallons from storage tank and 25 straight from tap, with anti nitrite dose of Seachem safe/prime to tap. Immediately after water change only 25% of the water will be at 3 ppm nitrites, the rest will be 0% in the DT for a total concentration of 0.75 ppm and your biofilter in your display tank should kill the nitrites very quickly sans harm, 25 gallons of tap also should not cause too wide a temp swing. Less than 10 degrees Fahrenheit seems safe per what I have read.
    By the way at 25% per day what is your nitrate level just prior to water change in your display tank. Depending on your tank set up nitrates are a fairly good proxy for determining if you are changing enough water.
    Finally, the water company is giving you the epa limit of 1.0 ppm nitrite nitrogen (meaning only the nitrogen volume not the additional oxygen is measured). If your assay measures NO2 that represents 3.29 ppm = 1 ppm nitrite nitrogen. Some home assays measure nitrite, some nitrite nitrogen. You need to know. My favorite, hanna checker measures nitrite nitrogen. I hate guessing colors.

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    Default Re: RO Water Question

    Thanks Willie!

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    Default Re: RO Water Question

    Hi Don,
    Sorry for my late response here. I was called out of town unexpectedly.

    You have correctly determined my issue. To condition my tap water I am using API Tap Water Conditioner to remove Chlorine and Chloramines and Seachem Neutral Regulator(phosphate buffer) to reduce my PH to 7.4 (from 8.9) and soften the water to KH 54 ppm. The phosphate buffer is providing a very stable PH. I will try your suggestions regarding increasing the water output.

    Regarding my Nitrate level with 25% water changes and the API test kit: All I can say is that I have been maintaining <10 ppm. I cannot detect color differences between 10 & 0 with the method I am currently using.

    Thanks,
    Wayne

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    Default Re: RO Water Question

    Hey if your nitrate level prior to changing 30% is 10 then you are golden and there isn't a reason to change more water unless you are doing something else to diminish nitrates that would diminish the value of that "canary in a coal mine"

    If OTOH your residual Nitrate is 10 just after changing your water (meaning your pre-change value was ~14) most folks would still feel you were in a good place although some argue that even near adult and adult discus should not be exposed to more than 10 ppm nitrates. I would certainly hold it to below 15.

    Neutral Regulator will reliably reduce your gH by precipitating Ca and Mg. Not sure of effect on kH.

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