Large water changes

Question

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The text above is a follow-up to ...

-----Question-----
Hi Karen!
I noticed you answered a question regarding large water changes, and you said that 75% water changes are a good thing. You also said that some fish breeders change 90% daily.

Here is my problem. I have a 75 gallon tank with 12 Cichlids. I have been doing water changes about 30% a week.
If I do any higher than that, my PH drops from 8.2 to about 6.4 because I use well water and the tap water PH is about 6.0.
How do people change 75 or 90% of the water without harming the fish with huge PH drops?
Do they pre-treat the new water with buffers before it goes in the tank?
I use Proper PH as a buffer, but there is no way I could pre-treat that much water.
Please explain what I can do.
Thanks,
Joe

-----Answer-----
Dear Joe,
Do you use the pH buffer because of the pH dropping in the main aquarium overtime? If you have a good alkalinity level, you should constantly have a good pH level.

If you happen to keep an African cichlid tank which would require the higher pH levels, you may have to stick with the smaller water changes. But you certainly have a problem here if your tank water is 8.2 and your source water for water changing is 6.0

Is it the pH buffer creating the 8.2 pH or is it rocks or decor that is dissolving minerals into the water? This is really hard to say because i'm not sure if you have African cichlids that require harder water and higher pH where rocks and buffers would be required to keep low-pH tap water at a preferable level. However, if you keep relatively softwater cichlids or those who are highly adaptable to varying levels of pH as most South American cichlids are...Then you may be able to use the tap water plain without any buffers added. But of course you must slowly acclimate the cichlids to the falling pH with a series of frequent small water changes with the lower pH over several weeks to a month or more.

Most aquarists fortunately have their tap water and their aquarium water with matching pH levels so large water changes are safe and fine. It's very good that you made sure to do the smaller water changes to prevent severe pH drops.

I really hope this helps and if I've left anything out, feel free to write again!

Best wishes and Happy holidays!
Karen~

Karen,
I have crushed coral substrate which is supposed to help with raising PH, and I also have Tuffa rocks and limestone which is supposed to also help with PH increase.
None of that seems to work, so the answer to your question is that I use the buffers to raise the PH because of the tap water issues. The PH isn't dropping. I need the buffers to maintain a PH near 8 or 8.2 for the African Malwai's.
I assume that I need to stick with small and more frequent water changes?
Thanks!

Answer
Hi Joe,
That helps clear some things up now!
You are certainly taking the proper measures for maintaining a high alkalinity and pH necessary for Lake Malawi cichlids. It's unfortunate however that your tap water has such a low pH. What is usually the case is aquarists have extremely high pH and hardness and want to keep softwater species but can't. I think you'll do excellent with smaller water changes and using the pH buffer. It's especially good that you have a large aquarium and a relatively low stocking level. You may be doing excellent at the rate of water changes and percentage right now. But if you raised it to 30% twice a week that would be excellent!

Keep in mind that the many aquarists who change 75% or more in their aquariums can be due to the fact that they keep very large or particularly messy fish such as Oscars or other very large cichlids. And breeders who may maintain very-well stocked tanks have an even greater need to do massive water changes for their rapidly growing fry.

As long as your african cichlids are healthy and happy, you are likely doing a very good job at taking care of them!

Best wishes,
Karen~