Please help with tap water ph vs tank water ph. Need some advice :)

[philipraposo198]

So I have had the 75g up and running now for 12 days (tank is cycled).
heavily planted with alot of DW
fish are:
2 golden rams
2 pearl gourami
25 cardinal tetra

I test my tank ph and it seems to sit at around 6.4-6.6. This is fine for my fish.
I test my tap like right from the tap and it shows 7.8

I fear that with doing WC's I am going to be creating to much of a PH swing, I don't want to cuz harm or stress to my fish if I don't have to.

Lets assume I do 15% wc weekly, how do i know how much of a ph difference this will cuz to my tank? i can't imagine it would go up to 7.8 but maybe 6.8 maybe 7? i don't know...

Anyone can hazard an experienced guess? What would you guys suggest I do to handle this situation? Because I plan to keep my tank under stocked and I have alot of plants and a big filter I would imagine I don't need to do WC's often. Which is probably a good thing as I don't want to be fluctuating my ph at all if possible.

I am trying to figure out whats a safe amount (%) to do as water changes.

[Khuligirl93]

How did you test your tap water pH? Did you test it immediately after it came out of the sink?
Also driftwood can cause the pH of the water to lower.
But having a pH at 6.5 is getting pretty low, because beneficial bacteria activity will be very slow, and it stops all together at a pH of 6.
In your situation I think smaller more frequent water changes would be best. Maybe 15% twice a week. Contrary to what a lot of people think, it's more stressful on the fish if you do water changes less often. Because the water has changed gradually further and further from the parameters of the fresh water the longer you wait in between changes.

[Mebbid]

This is actually really common and there are a few ways to handle this. Primarily this is caused by a buildup of gasses in the tapwater that raises the ph. Once they are degasses the ph will usually drop hence the disparity between tank and tap ph.

1. Take a half full bucket of tank water and then fill it with tap water. This will show you how much the ph will change. If its not more than a few points difference its fine to do 50% water changes.

2. If its still a huge swing you can use an aging barrel. Fill it with water and let it age overnight. This will equalize the ph. You can use a water pump to fill from the barrel.

3. Another approach is to improve the buffering capacity of your tank water. This can be done with a handfull of crushed coral in a mesh filter media bag thrown in your filter. Another option is a few small pieces of dry rock (rocks for a saltwater tank that are kept dry) They will both very very slowly dissolve in your tank raising your tanks ph slightly and buffering your water from ph swings.

[philipraposo198]

So if I take a sample of.my tank water and replicate a water change like25% your saying that will be a good enough estimation to get an idea of the swing?

Even thoughthe test is dealing with a max of 5g and my tank is 75g? Amount of pH change will be consistent between the 2?

[Mebbid]

Originally Posted by philipraposo198

So if I take a sample of.my tank water and replicate a water change like25% your saying that will be a good enough estimation to get an idea of the swing?

Even thoughthe test is dealing with a max of 5g and my tank is 75g? Amount of pH change will be consistent between the 2?

yep, the pH swing will be regulated by the buffers in the water. Whether it's a 10,000 gallon tank or a 10 gallon tank there shouldn't be any difference between the two.