With the wet spring this year and a few times in the past, We've had a few panicked calls about new ponds with low pH(5.0-5.5) and low Alkalinity(near 0). Its important to let a new pond sit for at least a few weeks after you get torrential downpours to allow your pH and alkalinity to adjust before jumping the gun and calling the lime truck. Rainwater is around 5.3 pH and 0 Alkalinity. I've had up to 30 acre lakes have 5.3 pH a week after filling up to 60-70% full. Then a month or so later its 7.5, 50 alkalinity and had a decent bloom. I would recommend waiting at least a month on a new lake after any big rain before testing the water, it'll help keep your wallet full and your sanity intact.