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Moving fish from high PH to low PH

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  • Moving fish from high PH to low PH

    I live it a very hard water area with a Tap water PH of just under 8 and very high hardness.

    With CO2 and ADA substrate I'm expecting my PH to drop to somewhere between 6-7 (only just set up so not measuring anything yet).

    The problem is my LFS uses the local tap water so how well are fish going to deal with the sudden shift in PH and what is the best way to acclimitise them?

    Ideally I know a 2nd tank would always be the best bet but I dont really have space for it at the moment. Is this going to be the only way to do it though (have a 2nd tank with tap water PH then over the course of a couple of weeks lower the PH and hardness)?

    I have read in some places that a change of PH will not cause any long term damage to your fish and just going through the normal process will be fine. But then I have read elsewhere that a PH shift of more then 1PH will stress a lot of fish close to death.

    I think what would probably be worse then the change in PH would be the change in hardness (doesnt this change the osmetic pressure?)

    Any advice would be great as i cant seem to find two sources that agree at the moment

  • #2
    Well here is what I do when I buy fish from the store.

    First, my tap water here is about 7.1 ph using a drop test kit. The LFS has about the same PH for their fish tanks. I run my CO2 non stop now using a manual adjusted bubble counter for 11 hours a day. I do have a Pinpoint PH controller but no equipment is attached to it anymore. The PH controller will read about 6.10 PH at the start of the day and levels off at 5.60 PH by late afternoon. I know this seem like REALLY acidic water but I have alot of surface movement and large CO2 return spray bar in the tank (130g). I see fish stress when the PH reads close to <5.50 PH on the controller.

    So back to bringing fish home in a bag of 7.0PH water and putting them in a tank with <6.0 PH. There is really 2 options I would recommend. Wait to buy fish on the day you do a water change. Most likely when you refill the tank with tap water the PH and temperature will be close to whats in the fish's bag.

    If you want to add fish on a non water change day I would suggest waiting until the end of the day when you turn the CO2 off for the night. With good surface movement and the CO2 off the PH will rise towards nuetral/base, easier on the new fish.

    At this point,I float the bag, sealed, for about 10 min (my water temp is +-82*f). After 10 min I add about 1/8 of the qty of water in the bag, to the bag with tank water and wait 5 min. After 5 min I repeat, its usually the 2nd dose of tank water that I sometimes see the fish in the bag start to complain. If they do I drop my air bubbler into the bag and add some O2. I keep on adding tank water slowly until the fish adjust to the lower PH. The air stone helps to reduce stress and only brings the PH up slowly. The fish are usually good to go at this point and I free them into the tank.

    There has been a few times when I added fish and they still gasped at the surface, I just turned on the air bubbler in the tank for a few hours (used manually for emergencies) with the CO2 off and sometimes lights off if its late enough. Anyway, the next day the CO2 will kick on and the PH will slowly come down and the fishes are all happy.

    Anyway, this is my method and I have never lost any newly bought fish. I know for sure that floating the bag for 10 mintutes and dumping the fish in there is a one way ticket down the porcelain highway.

    Good luck!


    • #3
      Thanks for the reply. This is pretty much what I do anyway when I introduce fish and its good to know that I should be able to do it without having to set up a second tank. I will do a couple of test runs first without fish just to get a feel for how much the PH changes and how quickly


      • #4
        Originally posted by Barney View Post

        I think what would probably be worse then the change in PH would be the change in hardness (doesnt this change the osmetic pressure?)

        Any advice would be great as i cant seem to find two sources that agree at the moment

        This is correct. Fish do not read ph, they read TDS of which hardness is a part of. Your aquasoil will soften the water more when first used and decline after that. A drip every second or two into an open container that the fish are in untill the water volume has doubled or tripled will make the transition the easyest on them. If the trip has been very long, ie shipped to you, you will need stuff on hand to neutralize ammonia so the aclimation process doesn't prolong their contact with that.

        I just took some apistos from the store's reconstituted RO water to my liquid rock useing this method and had no signs of stress beyond normal for bringing fish home.