Pond Boss Forums GENERAL QUESTIONS Water chemistry New Pond. High PH. Need help!

In April we broke ground and I finally got my dream of a pond in my back yard. Due to the sandy soil, we had to put in a liner. I also didn't have a water source, but we have a high water table, so I dug a well to fill and feed the pond. I know these are not ideal conditions, but I didn't have a lot of other options to get a pond on my property (without moving). The pond is about 85x42 feet in an oval. It slopes 3 to 1 into the center at a max depth of about 6 feet. I figure it is about 60,000 Gallons (give or take). The well water feeds into a waterfall on one corner of the pond, then the water overflows out the opposite corner into a lower swampy area in the property. I also just got an aerator, which I was running 24/7 until I read on this forum that I should only run it at night to keep the temperature down. I've not added anything to the pond except a little Blue/Green Dye. We have been loving it! Next step is fish.

Not sure if this link will work but I put the project on Instagram with time lapse video of digging and liner installation. If you are interested - I think you have to have an account and log into Instagram though.

https://www.instagram.com/p/CCdwPAvHTtF/ or look up @Trapperinator on IG.

We dug the pond in a very dry spring when the water table was low. I was paranoid about the pond liner being pushed up by our ground water when the neighboring farmers start to irrigate. So I decided to pour concrete on top on the liner in the bottom to secure it (It's not going anywhere). I also added rocks and sand on top of the liner. It's doing its job, but I did not consider what the concrete might do to the pH. I'm guessing the concrete is leaching out some lime or something and raising my pH. I have a high pH of 9 or greater (the kit I have only goes to 9). My well water in right about 7, so it's not my water source. I assumed that eventually the pH may drop as I'm feeding between 2,000-4000 gallons of new neutral water from my well each day sending the same amount out the overflow. But so far, still very high pH.

I'm planning on putting some BG in there in a week or 2, but the fish guy told me I need to get my pH down or I'll likely have stressed or dead fish. He recommended I just go to the pool supply store and get some PH reducer.

My Alkalinity is high. I bought 10 pounds of Sodium Bisulfate from Lowes and 15 pounds of Alum from Amazon. I was going to add some tonight, but thought I'd ask some advice first. Do I just sprinkle in the pond, mix with water first and pour into the pond? I'm also reading that the Alum will cause a sludge that will sink or float in the pond. Is that safe to leave on the bottom of the pond with my kids swimming in it? I assume it will just be part of the slime on the bottom?

Thanks

Trapper

I recommend you wait for advise from one of the knowledgable folks here! Good luck!

See this

https://srac.tamu.edu/fact-sheets/serve/205

Thanks for the link. Very interesting. Makes me wonder since I dont have fish yet, only a few plants and Algal growth, if low CO2 is largely to blame? Does that mean that adding fish would reduce ph since they breath oxygen and exhale co2?

This also confirms that the Alum would be good, but I still am not sure how to apply it and what to expect with the agglomerations it makes. If anyone with Alum experience can weigh in, I'd appreciate it.

Does anyone have a good source for Alum online? Pretty sure I overpaid for 15 lbs. on Amazon. My local farm store couldn't find a supplier.

Try calling one of these that are close to you:

https://www.suppliersof.com/fertilizers-agricultural-chemicals/us/Utah/80363437

I'd go with Helena Chemical if they were close enough to you. Watch that you don't drop the pH too quickly.