Never have I seen it rain so heavily

[Meyer Jordan]

so what is you idea of what caused the ph change?

The immediate question that comes to mind is...What was your Alkalinity before the rain? Also Gh and KH would need to be factored in, what were those levels?
If flooding was occurring, was there any evidence of run-off?
Also, did your other pond experience the same drop in pH?

 

[mrsclem]

The KH has always been low in this pond. I have used the crushed oyster shells in the past but did not have any put in recently. The last KH was 96. The pond is raised so no chance of run-off. I had put a roll of reed fencing over part of the pond and filters for shade. This may have something to do with it. The other pond has lots of plants and a bog filter. KH there is usually over 140. I haven't tested the other pond as there doesn't seem to be any problems but planning on retesting both ponds today.