Rain water and Pond Ph

[juanprieto]

We are in the middle of a tropical depression hovering over my pond in Miami. The Ph in my pond is usually 7.6-7.8. Rainwater has a Ph of about 5.5-6.0. We are expecting up to 8 inches of rain over the next 24 hours. Should I be concerned about the Ph shift over a short period time? My pond is 2,500 gallons. I will test the PH after the storm passes but just wanted to check in and see if anyone here has had a similar situation. If the Ph has dropped significantly is baking soda the correct additive for the pond and how much?
Thanks!

 

[Mgessert]

Beautifu! I’m in north FL and we had seven inches in 24 hrs. last week. My pH barely moved. I routinely use rainwater to top off my pond. Did you have any trouble with it during last year’s summer rains?

 

[WaterGardener]

When we are expecting a lot if rain I go ahead and boost the KH with baking soda before it rains. That prevents any drop in pH.

The pH in my pond will definitely drop with heavy rain so I would rather be proactive than try to correct it afterwards.

 

[BKHpondcritters]

I do the same as WaterGardener & make sure the kh is nice & high. After any significant rain events I also recheck the kh to see if I need to add any additional baking soda then as well.

 

[juanprieto]

Beautifu! I’m in north FL and we had seven inches in 24 hrs. last week. My pH barely moved. I routinely use rainwater to top off my pond. Did you have any trouble with it during last year’s summer rains?

No. This is the first big rain I get after finishing it. I completed it about 8 months ago. I have been using tap water to top it off with chlorine remover.

 

[juanprieto]

When we are expecting a lot if rain I go ahead and boost the KH with baking soda before it rains. That prevents any drop in pH.

The pH in my pond will definitely drop with heavy rain so I would rather be proactive than try to correct it afterwards.

When we are expecting a lot if rain I go ahead and boost the KH with baking soda before it rains. That prevents any drop in pH.

The pH in my pond will definitely drop with heavy rain so I would rather be proactive than try to correct it afterwards.

Ok good info. Thanks! By KH I assume you mean Carbonate Hardness? If so then its at a healthy 120 before the rain.

 

[WaterGardener]

Yes, carbonate hardness. That alkalinity buffers the acid and prevents the pH from dropping.

 

[juanprieto]

Update: Initial KH was 150. It dropped to about 60 after all the rain. I researched that at that value it is too low to buffer the Ph effectively so I added 2 cups baking soda today. Will re-check tomorrow and add more if still low. From what I have researched 150-200 is a good number to be at. I will be buying more baking soda as it rains a lot here in the summer! To all that answered thanks for the help. I had never had this situation come up yet and it was a good learning experience.

 

[WaterGardener]

If you have Costco stores, they sell large bags of baking soda, 10 pounds or so, for a very reasonable price. Much less expensive than the little boxes from the grocery store.

 

[BKHpondcritters]

If you have Costco stores, they sell large bags of baking soda, 10 pounds or so, for a very reasonable price. Much less expensive than the little boxes from the grocery store.

Our Walmart carries 12# bags of it in the outdoor garden (pool supply) area during the summer. I usually buy a couple to have on hand.

 

[GBBUDD]

I do the same as WaterGardener & make sure the kh is nice & high. After any significant rain events I also recheck the kh to see if I need to add any additional baking soda then as well.

And what is high kh I just tested and kh was 9 gh was 7

 

[BKHpondcritters]

And what is high kh I just tested and kh was 9 gh was 7

If you mean the kh tested out at 9 drops that's a nice number. I don't have my kit in front of me but, iirc, that puts the level in the 150 - 160ish range (I generally try to keep it between 100 - 200, definitely no lower than 100)

 

[GBBUDD]

Yes 9 drops . Thanks and that's doing nothing to help boost or maintain sweet

 

[WaterGardener]

Not all of us are as fortunate.

I keep the KH in my pond around 200, but will boost it as high as 300 if heavy rain is expected.

 

[GBBUDD]

Do oyster shells help to boost