Can I use pure vinegar to drop my ph for my water changes

[jay179]

Can I use pure vinegar to drop my ph for water changes. The ph of my tank is 8.4.The water I am going to use for my water change has a ph of 8.8.

[ccCapt]

You can, but I would not recommend doing it. How big of a water change are we talking about? If you did a 20% water change with water that is 8.8 pH and your tank is at 8.4, the water change will only bring the pH in the tank up to 8.48.

[jay179]

I usually do a 5 gallon water change a week for my 75 gallon. Is that sufficient. The last week of the month I'll do two 5 gallon changes.Usually about 5 5 gallon changes a month.

[Crepe]

5 gallons a week is only about 7%. You should be doing 15-30%.

[cmor1701d]

I would suggest a 10% weekly or 20% every other week schedule for PWC's. Some do more, many do less, but there's no denyng the benefit of a PWC.

So think about upping your weekly schedule to 10 gallons. Pick up a 20 gallon Brute (by Rubbermaid) trash can to mix the water.

But first, what are you using for source water? Tap?

a RODI unit will strip all buffering capacity out of the water as well as most everything else. Then your salt mix should get you to the ~8.2 range.

[thincat]

Originally Posted by ccCapt

You can, but I would not recommend doing it. How big of a water change are we talking about? If you did a 20% water change with water that is 8.8 pH and your tank is at 8.4, the water change will only bring the pH in the tank up to 8.48.

Larry, how did you come up with "8.48"?

[ccCapt]

I guess the easiest way to explain it doing a 20% change is....
8.4pH x .8 (80% of remaining water) = 6.72
8.8pH x .2 (20% of new water) = 1.76
100% = 8.48 pH

[thincat]

Thanks Larry

[jay179]

I only have 3 fish,Two yellow tails and a maroon clownfish. I have a 75 gallon tank with 105 pounds of live rock and 60 pounds of live sand to go along with 15 pounds of argonite. My nitrate levels have ben 5 ppms and below for the last month. If I add more fish I may up my daily changes to 10 gallons a week. I change 25 percent of the water monthly. I use RO/DI water. I have a four stage system.

[Kurt_Nelson]

Originally Posted by ccCapt

I guess the easiest way to explain it doing a 20% change is....
8.4pH x .8 (80% of remaining water) = 6.72
8.8pH x .2 (20% of new water) = 1.76
100% = 8.48 pH

pH isn't linear... it's logarithmic... so I don't think it works like that. I think. Maybe.

[ccCapt]

Kurt, you are correct, but the difference is so slight (assuming all water parameters of both the new and old water are similar) the forumla above gives you a good idea of how small the change would be.