Announcement

Collapse
No announcement yet.

Phosphoric acid to lower ph?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Phosphoric acid to lower ph?

    Recently, my friend, an arowana (scleropages formosus) hobbyist, told me that to lower ph in his pond, he has constantly been using phosphoric acid. And after all these years (4 years to be exact), there is no visible harm to the fish.

    I wonder if this acid can also be used in koi pond! Any comment, please.
  • #2

    I have some experience using phosphoric acid, but not with koi. Used with care it can be successfully employed to help alter water parameters to match the low mineral content, soft, acidic water of rainforest waterbodies. However, the phosphorous acts as a fertilizer and will contribute to algae blooms etc. It is not reliable with high alkalinity water, and results in many pH fluctuations dangerous to fish. I ceased using it long ago and substituted rainwater in which sphagnum moss had soaked for a few weeks to create soft, acidic water for aquarium species needing those conditions. [Gave them up eventually because simply too much work.]

    I do not believe the water for koi should be treated to alter pH unless the pH is so high as to be wholly unsuitable. That is rarely true. If that is the case, as much as I love koi, I'd have to recommend keeping other species. In the tropics, a pond of african cichlids would be a beautiful sight ... not koi, but one can learn to appreciate other things. Eventually, the pH fluctuations will cause serious problems. Stability is more important than "perfect" pH.

    Comment

    • #3

      What Mike said is true. Phosphoric acid is a commonly used source of phosphate for fish ponds used for rearing fish larvea to fry.

      I'd not use it in any pond subject to any sunlight or other light source as phosphate is usually the limiting nutrient and will cause an algal bloom from hell in a nitrate rich environment.

      I've found that if it is necessary to adjust pH, hydrochloric acid seems to be best as it adds "nothing" to the water but hydrogen and chloride ions.

      I also agree that with most cases, stability is more important than any particular number with referrence to pH.

      However, in the case of trying to bring fish into show form, then pH plays an important role with respect to the overall condition of the show animal.

      Brett
      Brett

      Comment

      • #4

        Brett: You should expand on "pH & show form" on the thread about finishing.

        Comment

        • #5

          Thanks Mike and Brett. I'll convey this information to my friend.

          Before being treated with phosphoric acid, the ph of his pond was 9.5. Is this level 'so high' that it need to be treated (well maybe with hydrochloric acid as Brett suggested), or should it be left alone as long as it is stable, as Mike said.

          And for koi, what would be the maximum ph that is considered as still acceptable?

          Comment

          • #6

            If the koi are still alive it must not be too high. However, that is really a bit extreme for koi.

            You really need to know your other water quality parameters, especially hardness and alkalinity. This might help explain the reason for your high pH and provide some clues of how best to manage it.

            This water is either very hard, salty, wierd, or very soft. If it is very soft, a little acid might be way too much. If hard, it might take quite a bit to have any effect at all. If its wierd, there is no telling what might happen. I've had experiences with all sorts, even wierd.

            I would want to do what it took to bring the pH down to a more moderate level. It might be very simple or could be very complex. If I had more information I might could suggest a way to manage the situation.

            Brett
            Brett

            Comment

            • #7

              Unfortunately Brett, other parameters have not been tested. I can only gathered the following data:
              - pond size: 120 tons (concrete pond)
              - fresh water is continuously supplied at a rate of 4 tons per day
              - ph of fresh water is 7, with TDS of about 180 ppm

              My question is, if fresh water added has a ph of 7, why it rises to 9.5 in the pond? Is this a sign of bad filter?

              I'll ask to have ammonia, nitrite and nitrate, hardnes and alkalinity tested this coming few days and inform you of the result!

              Comment

              • #8

                If you mean the new water has pH of 7.0 but it rises to 9.5 in the pond, then forget about treating the water. I suspect the pond is less than a year old and the concrete is leaching. If this is the case, it will gradually improve on its own. To obtain quick improvement, your friend should read up on treating the concrete. Using a sealer might be a challenge if algae etc already getting established. I'd expect it is more practical to empty the pond & use an inexpensive mild acid (muriatic acid is often suggested) to neutralize the alkalinity on the surface of the concrete. Concrete will still leach, but more slowly.

                Comment

                • #9

                  Kiky,

                  Hope you dont mind me asking, but is the fresh water's pH tested as from the tap? If it is Chlorinated and tested 'fresh' from the tap, it may affect the reading.

                  As an example, my tap water tested direct, has a pH of 7.6. If an amount is put into a bucket and aerated, even after an hour or so, the pH will have risen to 8.6. The aeration evaporates the Chlorine, so the true pH valve was actually 8.6.

                  Although 9+ is high, it may be it's true value and you could be chasing a problem which is not there at all.

                  Regards, Bob
                  Regards, Bob
                  ><{{{{º> ><{{{{º> ><{{{{º>
                  <º}}}}>< <º}}}}><

                  Comment

                  • #10

                    Mike,

                    You are so right. My friend told me that this pond is indeed less than 0ne year old. I have informed him to have the water tested, as Brett suggested. He has brought sample of the pond water for analysis to the lab of the Health Department. Results will out in one week. And Mike, how long it will take for the ph to come down by itself, if left untreated? Since there are about 35 fishes with average size of 50 cm, it is inconvenient to empty the pond and have a muriatic acid treatment.

                    For Bob,

                    The water is from underground, from a deep well of 70 m sucked by a submersible pump. Do you have any experience with underground water?

                    Comment

                    • #11

                      Kiky,

                      Only that my water is also from a well/borehole, as probably are many people's. Is it pumped from the well, direct to the pond? Or is this 'town' water from a well, if so is any treatment added, like Chlorine?

                      Regards, Bob
                      Regards, Bob
                      ><{{{{º> ><{{{{º> ><{{{{º>
                      <º}}}}>< <º}}}}><

                      Comment

                      • #12

                        Kiky: I do not know how long it will take. From what I've read, it depends on the type of concrete, how it was applied, frequency of water changes, softness of the source water &amp; lots of other factors. It seems most concrete ponds stabilize after a year, with continual improvement along the way. I think the idea of testing the source water several hours or a day after it has been drawn is a good start to figuring out if it is the water or what happens to the water after it is in the pond. That informayion will narrow it down considerably. Let us know.

                        Comment

                        • #13

                          Bob,

                          The water is pumped directly from the well and collected in a large container. It is then distributed for both the pond and other household needs.

                          And Mike,

                          The fresh water has previously been tested and was found to be alright. So it definitely turned 'bad' in the pond!

                          Comment

                          • #14

                            So, we know that the high pH is caused by something in the pond, which is concrete and less than one year old. Seems likely it is the concrete leaching, but if there are any other alkaline materials in the pond (such as coral-based rock around edges, limestone used for decorative purposes in a waterfall, etc.), they could be a contributing source of high pH. If those possibilities are ruled out, you are left with how to address the high pH without removing the koi. I do not believe there is a quick solution, but I do have a simple one to suggest. But first, remember what I said above about avoiding pH fluctuations. You do not want to subject the koi to unstable conditions. It would be better to continue current practices and simply endure the high pH than have the fish subjected to large pH swings.

                            The leaching will reduce over time as the more soluble components of the concrete surface dissolve into the water column. The lower the pH of the water in contact with the surface of the concrete, the quicker neutralization of the surface will occur. (Note: It may never be truly "neutral". There may well be a continuing tendency to increase pH for many years, but at at a decreasing rate.) Also, soft water will speed the process, but too complex and impractical to address in your friend's situation. Once a thick growth of algae becomes established on the pond walls, there will likely be less effect on pH. You could use an acid additive, but you would need to be very careful and precise. The pH would need to be tested frequently and on a regular schedule every day (and night), with dosing in small quantities occurring on an almost continuous basis to prevent pH bounce. I do not believe it is practical.

                            So, that leaves water changes using the moderate pH source water. I personally believe in large water changes on as frequent a schedule as one can do them as part of a regular maintenance program, but large water changes would not be advisable in your situation. ... at least at first. I'd suggest trying daily 5% water changes. After a couple of weeks increase to 10% daily water changes. If this is too frequent due to work/lack of time, then do the water changes on alternate days. The important thing is to do them on a regular schedule and for them not to be so large that the koi have to endure a lot of fluctuation. (Dechlorinator is cheap, so use it.) Suggestion: Conduct a test by placing 2 gallons of the high pH pond water in a large container, and add 1 gallon of the source water. Measure the pH immediately. Then measure pH again in 5-6 hours. This will indicate the extent of pH fluctuation doing a 30% water change. If the first reading lowers the pH by more than 0.5 (some would say 0.2) you cannot change so much. If the second reading shows the pH rising to be close to the original pH in just 5 hours, then you know that there is a high buffering capacity in the pond water that will cause pH bounce, so you will want to limit the size of the water changes so that no more than a 0.2 pH differential occurs between completion of the water change and 5 hours later. There are many who would disagree with subjecting koi to a 0.5 pH shift during a water change. I would not do it to my own koi. Nonetheless, assuming the replacement water is introduced over a period of 2 hours or more, I believe it will be O.K.[BUT ABSOLUTELY NOT ANY MORE THAN THAT], but not if the koi will be re-subjected to a pH increase of more than 0.2 in the 5 hours following. ( I view this as maximum fluctuation limits, not desirable ranges.) Try testing different water change percentages in the container until you find the size of water change that stays within these limits. In your friend's pond, it may be that no more than 5% or 10% can ever be changed without subjecting the koi to too much fluctuation. The goal is to gradually increase the rate of water changes until the leaching from the concrete is balanced out at a pH level deemed acceptable. It may take months, but I expect over a period of 3 months it will reach a stable point, if not sooner. If this sounds like too much work, then do not start a process that won't be followed through. Good luck.

                            Comment

                            • #15

                              Kiky: Looking back over this thread, I see that there is continual inflow of fresh 7.0 water. If the inflow could be increased to 2 or 3 times the current rate, and kept at that high rate for several months, I think you would see the problem solve itself.

                              Comment

                              All content and images copyright of: Koi-bito.com
                              Working...
                              X