Jacob’s thread taken up again

Also won­der­ing how slow accli­ma­tion should be, the water is pH 4.2 and very soft, the fish will prob­a­bly be in water 6.5. Not in black­wa­ter, just mildly acidic, so I won­der how long to take accli­mat­ing them. I know water changes are done where they raise the pH and it only tem­porar­ily stresses the fish but since it would be a whole new envi­ron­ment I thought it might require a slow intro­duc­tion. (And that is usu­ally a raise in ph where this is low­er­ing it, which is sup­posed to be worse for fish.)

Won’t be that bad of a shock, recent tests say water in tank is 5.7 and water for water changes is 6.2
Will have to fil­ter the new water for longer to get lower ph.

1. UV-​filtration: There are no def­i­nite results of long-​time exper­i­ments. The tech­nique is use­ful for short-​time appli­ca­tion for well-​defined sit­u­a­tions (i.e. the removal of chem­i­cal addi­tives or the destruc­tion of “green water”) but not as a per­ma­nent part of a sta­ble aquar­ium sys­tem. The effect depends on the elec­tri­cal details of the lamp, on the quan­tity of the water-​flow and other para­me­ters. Humine sub­stances may very well be deformed and destroyed; they are chem­i­cally not uni­for­mous. In any case UV-​filtration a deep tech­ni­cal manip­u­la­tion of the water-​body and the whole living-​system (e.g. Fe which plants need for grow­ing will be severely affected by it). For a healthy and sta­ble black­wa­ter tank it is unnec­es­sary and even dan­ger­ous.
2. pH-​shock: You should be care­ful in any case, espe­cially if the dif­fer­ence is a full pH-​step or more. If you have sen­si­tive and valu­able fish (as Parosphromenus or Sphaerichthys) you should adjust the water in no less than one hour, maybe more. Very cau­tious peo­ple do it by a “drip-​method”.
On the other hand: I have often adjusted waters for and with Parosphromenus much more quickly up and down, some­times one value within a quar­ter of an hour, and there was never a prob­lem. It depends on the indi­vid­ual fish. Healthy and vital fish will mostly stay that (not if the dif­fer­ence is big­ger!). But this is not a rec­om­men­da­tion. There were sit­u­a­tions in which the fish sig­nalled dis­com­fort under the new con­di­tions. In two or three cases I had quickly to lessen the dif­fer­ence.
If you take time, one hour at least, bet­ter two, you will be on the safe side, espe­cially with a dif­fer­ence of half a pH-​step or less. Remind: Often, the fish are some­how weak­ened. Then my advice to be cau­tious holds so much the more.