Water source is changing with a drastic pH difference.

[jefferz]

The company that provides my water is switching sources in a couple of weeks, and there will be a drastic pH difference.
Currently, my pH out of the tap, and in my tank, is 6.4.  They're saying the pH after the switch over is going to be 8.2.
My tank is a heavily planted 20 gallon with zebra danios, a bristle nose pleco, and tons of neocaridina shrimp.  I'd have to tear down the tank to catch all the inhabitants to do a drip acclimation, would be a major pain, which I'd like to avoid.
I have 2 50 gallon rubbermaid trash cans that I've filled with the current 6.4pH water. 

My normal water change is 5 gallons, 25%, every week.  When they do finally switch the water source over, I was thinking of doing a water change with 4 gallons of the 6.4pH water, and 1 gallon of the 8.2pH water.  Do that for 2 weeks.  Then do water changes with 3 gallons of the 6.4pH water, and 2 gallons of the 8.2pH water.  Do that for a couple of weeks.  Then 2 gallons of 6.4pH, and 3 gallons of 8.2ph.  Then continue that trend until I'm just using 5 gallons of 8.2pH water.

Would that be too quick of a pH change?  
I know I could buy an RO system, then buffer my water down, but I'd like to just be able to use my water out of the tap without having to add chemicals all the time.

Thanks in advance.

[Guppysnail]

All the fish you listed can acclimate to the new water. 
I have gotten fish from friends that had soft low ph water. I have also hatched eggs in low ph soft water. 
Hiw I acclimate them to my 7.8-8.2 water is each week at water change I add my tap water to the ongoing water. Each week sometime 2x a week depending on how fast I need it to happen I increase the amount of tap going in until I’m up to just adding tap water. 
I also have given friends with very soft water fish and to help them with that transition I buy gallons of distilled or to water and add that to the ongoing water increasing the amount each WC until I’m At their ph. 
I have read .2 degree ph Changes a day is safe I’ll defer to @Odd Duck for more specifics. 
 

In other words your plan sounds great but you may be able to accomplish your end ph goal a bit sooner. 

[nabokovfan87]

First thing is going to be that it's 8.2 PH out of the tap, but what is it after 24 hours of off-gas testing?  How stable is that water at that new PH, what is the KH change going to be?

I would try to store as much water as you can in some sort of covered container with aeration, so that you can acclimate the shrimp as slowly as possible to new hardness.  If that KH is sky high, then you're going to run into mass molting issues.  Make sure you're always slowly adding water into those tanks for water changes while all of this is happening and for the time following that change.  (let's say at least a good 4-6 water changes thereafter.

When I have issues with the tap I monitor two main data points until they equalize.
A.  What are the parameters at the tap, after off-gassing
B.  What are the parameters of the tank

Then it's just a matter of time and balancing what need be until the parameters fit the species that are sensitive.  In this case it would be the Neos I think.

On 5/6/2023 at 4:37 AM, jefferz said:

My normal water change is 5 gallons, 25%, every week.  When they do finally switch the water source over, I was thinking of doing a water change with 4 gallons of the 6.4pH water, and 1 gallon of the 8.2pH water.  Do that for 2 weeks.  Then do water changes with 3 gallons of the 6.4pH water, and 2 gallons of the 8.2pH water.  Do that for a couple of weeks.  Then 2 gallons of 6.4pH, and 3 gallons of 8.2ph.  Then continue that trend until I'm just using 5 gallons of 8.2pH water.

Once you have the new water test it for GH/KH/PH.  It may not come all at once, but in waves.  I've experience shifting water that has been happening over months.

Take the water in Can 1 do your water change.  Fill that back up with water from the tap.  What that does is slowly mix/shift the parameters of the old and new water.  Repeat that again.  Let's say you use 15-20% of the can each time.....

First change: 0% new water in solution
Second: 15-20% new water in solution
Third: Less than ~30% new water in solution
Fourth: Less that ~40-45% new water in solution
etc.
(maybe at this point you add more of the old water from the other can into the solution to dilute it back, all determined by water testing analysis)

You'll be slowly diluting over to the newer water.   This allows you to keep a can of the old water at original parameters and then you have what amounts to a mixing station in the other can.

Edited May 7, 2023 by nabokovfan87
spacing

[Patrick_G]

That is quite a big change! I can see why you’re worried, but I’d follow @Guppysnail’s advice and do a .2 degrees PH change per day. 
 

I think this calculator should help with how much water to add each time. 
https://nextaquarium.com/water-change-calculator/

 

Edited May 7, 2023 by Patrick_G

[Lennie]

I would also def test the water for sure. My friend @beastie’s water company stats say 7.9 ph however she always read between 6.8-7.0 in all of her tanks. No buffer or aquasoil whatsoever.

So yea testing is a more guaranteed way to know. Then it sounds like a nice idea to follow up the ideas given above if there is actually a difference

[Odd Duck]

I think the shrimp may need a little help with a different water composition.  You may need to get RO water and remineralize it for your shrimp.

The fish are quite capable of handling much bigger pH and GH/KH shifts.  I think doing twice weekly 10 water changes might be easier than loads of mixing, but I would tend to save your water for doing the water changes on your shrimp. I guess I should ask if your shrimp are mixed in with the fish your tanks?  If not in separate tanks, then you’ll have to do smaller water changes or mix gradually like your current plan or your shrimp may not prosper in the long run.