I am not a chemist, but I'll give it a go.

What is the PH out of the tap? Ours is pretty alkaline in this part of Texas, lots of limestone in the aquifers. I have 8.0 out of the tap.

Liner or concrete pond? Any cinder blocks or anything else that could be leaching lime?

Lot of exclamation points there. You probably didn't need to worry, although 30 goldfish were probably too many, at least after they grew. You didn't say that your fish appeared to be ill. You said a pH 'past' 9. I assume that you meant less than 10; or was 9 the top end of your test range?

If fish were OK, you probably didn't need to worry at all. It is possible that your test kit is old or inaccurate although noting that your tap appeared to be pH 7.5 slightly suggests that it might be working reasonably well. One small point: clean tap water may only have minimal amounts of stuff in it and the addition of a drop of lemon juice or something could drop (or raise if caustic) the pH by several points (perhaps thousands fold increase in acidity). On the other hand, a drop of lemon juice in 800 gallons of stuff and junk would not be noticed.

Anyway: a pH well over 9 might not be ideal, but it is probably OK. I suspect that the tomato spikes are likely to be a little acidic and wouldn't increase your problems, and even if they were a little basic (caustic), it wouldn't change things because you may be sitting strongly buffered at pH 9 anyway. For curiosity and perhaps for anxiety decrease, you could try reading pond pH in the early morning.

I posted a question last week - two actually, I have had no response.
I did a search using your member name and found "Adding Salt after water exchange" and it is in the "Ponds & Aquatic Plants Forum" but I don't see it in the forum's thread list and don't know why. The another question you posted I can't find. So you didn't get a response because I'm guessing no one could see your post. It's always OK after a day or so to make a follow up post saying something like "Anyone?". That bumps your question back to the top of the list where more people can see it, or in this case, maybe make it visible.

We have quite the dilemma. Our PH in our pond was past 9!!!
That's only a dilemma if you consider it a dilemma for some reason. It would help if you explained why you don't want a pH of 9 and also what pH you would like to have.

Goldfish and koi are perfectly fine in a pH of 9. Many of the finest koi keepers run ponds with pH in the 8.4 to 9 range and prefer that range because it makes stable pH easier, safer.

My guess, based on the 3 exclamation points, is the test kit said 9 pH is high? Or some pond expert told you this? Well, 9 pH is high, but that doesn't mean harmful. The optimal room temperature for humans is 72F. While we call 80-90F warm or hot we still do just fine.

But some people do like to keep pH at some level for specific reasons which is why I asked what level you want and why.

I know we had way to many goldfish in it.
The number of fish wouldn't have anything to do with high pH. The opposite is true. High fish load tends to drive pH down and people with that type of pond have to add chemicals to keep pH up and stable.

Without knowing when and how often you tested pH, and without knowing what scale 4 KH is, it is possible for you to measure 9 pH and and hour later measure 6 pH.

So we done a 1/3 water changer over 2 weekends in a row, took 25 goldfish out of our pond. We now have 8.
Are you trying to say 17 fish died? Your other post said you lost 6 fish but didn't mention any water change. It would be a big help you provided a list of events in chronological order, with dates and times of day (pH level changes throughout the day by a lot sometimes).

However, it wouldn't surprise me at all that those water changes contributed to fish loss. Water changes are safe unless great care is taken and a fair amount of pond understanding is known.

Our pond is about an 800 gallon pond. No nitrite problems, no ammonia problems, kh is 4.
I wish I had a nickle for every time someone posted "No nitrite problems, no ammonia problems" only to find out much later, after asking for test results many times, that there was indeed an ammonia problem. Post test result.

When posting test results be honest and as precise as you can. When pushed for test results I've seen people get mad and post 0 nitrite, 0 ammonia just to shut up the people asking for test results.

Be precise. The KH test result is 4....but 4 what? Drops? German degrees (°dKH)? Parts per million (ppm)? 4 doesn't tell us anything. If it is 4 drops your kit will explain how to convert that to dKH or ppm which is what you and we need.

When we checked our PH from our outside faucet it is 7.5
Testing pH is extremely difficult. Well testing is easy, but getting a good reading is difficult. CO2 in the water makes the water more acid. So right out of the tap pH can be low. Wait an hour and it can be different. Shake the water and pH can change.

You are absolutely right, pH is confusing. How's your throwing arm? My advice is to:

1. Place your pH test kit into your throwing arm hand.
2. Go into your backyard.
3. Throw it as far as you can.
4. Forget about pH.

Instead measure KH. KH is much easier to understand, easy to adjust and most importantly tells you what pH is today, tomorrow and next week. Testing pH only tells you what pH is at that exact minute of the day. It can be much different in 12 hours or after a rain. It's worst than worthless info because it drives people to do all kinds of harmful stuff to the pond, like massive water changes.

Learn about pH buffering instead of trying to understand pH.

Well said, WB Guy. Especially like the way you ended it.

Read about using baking soda as a buffer to stop any pH swings due to acidic rain or other reasons. If your fish are fine, then you do not have to worry about your so called high pH.