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Reverse Osmosis Filter?

Discussion in 'Water Chemistry' started by James Doerflinger, Mar 10, 2017.

  1. James Doerflinger

    James Doerflinger New Member

    Joined:
    Dec 28, 2016
    Messages:
    4
    After running my basement, 100 gallon home system for over a year, battling high PH, I finally tested for carbonates and hardness on my city tap water. PH is 8.4, general and carbonate hardness were out of the range of the test strips, right out of the faucet. This explained why the top inch of my hydroton was turning white, fish were dying, and nothing would grow over an inch.

    I removed and hand washed the hydroton but it didn't do anything to fix the problem. I then got a RO filter, changed out 3/4 of the water with the filtered water, and continue to top off and do regular water changes with RO water. I am compensating for the loss of minerals with Maxicrop liquid seaweed with iron.

    My PH is still the same and so is the carbonate hardness. I am hoping that with time, the natural process, and continued use of RO water that this will eventually correct itself. I'm really hoping that I won't have to replace the hydroton, as I have 10 bags of it in the system and it is quite expensive.

    I am wondering if I'm on the right track with this thinking. Is my hydroton shot? Can it be saved with an acid bath? What is an appropriate level of carbonate hardness for adequate buffering?

    Everything else in the system is fine. Ammonia, nitrites, and nitrates all read 0. It's just the PH stuck at 8.4 and the record carbonates that are punishing me.

    I have found that bok choy loves living this way. So does kohlrabi, but the root system was so intense that I ended up with the equivalent of rocks in a wool blanket.

    I am setting up a 7 tank connected systen to start breeding tilapia. My plan is to fill it all with RO water and then add just enough tap water, treated with the usual tap conditioner chemicals, to get it to a decent PH and carbonate range before adding the fish.

    What say you, oh experts of the interwebs? Please and thank you in advance!

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  2. Mel Redcap

    Mel Redcap Active Member

    Joined:
    Jan 21, 2016
    Messages:
    271
    Country:
    Australia
    State:
    ACT
    City:
    Canberra
    Well, the good news is that your hydroton should be fine, but I think you're going to have to start using acid to bring the pH down. Nitrification does eventually lower the pH, but it's a very slow process unless you're working with high fish/feed levels, and if your fish aren't doing well with the high pH and you have a low stocking level (which I guess you do since your nitrates are zero!) it won't do enough to overcome the buffers in your water.

    First, get some hydrochloric acid; it should be available in big hardware stores, since it gets used to etch pavers etc before painting them and to clean some types of stain, or pool supply stores. If there are different concentrations available and you're not sure which to get, it's probably best to get the lowest concentration as this will be the easiest to work with! Definitely read the handling instructions and wear gloves, be careful etc.

    You'll need a large container to hold your topup water for treatment. (Always treat your topup water instead of putting acid directly into your system so you don't end up stressing or killing your fish and possibly crashing your bacterial colony.) Add acid to the water until the pH reads about 6.5, then leave it for 12 to 24 hours before testing again; if it's bounced back up, keep doing this until the pH stays stable at that level. If you start with RO water this stage will go faster and take less acid; keep track of how much acid you need to use in how much water to achieve this, so in future you can add it in one go and then just wait 24 hours for it to stabilise.

    Once you've got your nice big container of de-buffered low-pH water, you can do small water changes every couple of days to bring your system pH down, emphasis on the small because you don't want to be shifting the system pH fast! It will work, but the gentler you are about it the better your fish, bacteria, and plants will handle the change.

    You may need to keep treating your topup water for a while after you get your system pH down to optimum levels, or alternating between untreated and treated water topups, depending on what pH your RO water is at. Have you tested it? Also, you mentioned using test strips - they're nice and convenient, but they're a lot less accurate than a good liquid test kit (which will also be able to tell you exactly how hard your tap water is), so it's probably worthwhile getting an API kit or similar.

    Good luck!
     
  3. James Doerflinger

    James Doerflinger New Member

    Joined:
    Dec 28, 2016
    Messages:
    4
    Thanks. I know it takes a lot of time and effort to provide an excellent response like that.

    The RO ph is 6.2 so I'm still hoping to avoid acid. I will be using a 30 gallon tank just for holding and adjusting the top-off water.
    I just did a 100% water change yesterday. Today the ph is 7.2. I'll call that a win! We'll see what happens over the week.

    I have about 30 goldfish and pleco in a 100 gallon system feeding 5 grow beds that total an area about 3ft x 7ft, 1ft deep. I do believe that qualifies as a light load.

    I will be attaching my new 8 tank, 265 gallon system to the aquaponic system through a small syphon. The new system has its own filter. I'm hoping that a slow, constant flow through the grow beds will eliminate the need for water changes.

    I have an API test kit but have been using the test strips for hardness and cabonate hardness. I guess that since I'm expanding, it's time to science the $#!+ out of this!


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