Help! Left my water running!

[Connie H]

I added some water to my sump tank in the morning and forgot about it!!  It ran all day.....My ph is high off the charts now.  The fish seem ok (I use a chlorine filter on our tap water) and ate fairly well when I fed them.  And the water was clear, which it hasn't been for months :)  It was exciting to see all the fingerlings in the big tank that I didn't know existed...I'm guessing the effect on the fish may show up later?

Should I add anything to bring the ph down or just let it run?  I would say it was easily a 50%, maybe even 70% water change. 

My system: 275 IBC fish tank, Two 150 gallon IBC grow beds, 75 gallon sump tank, forty 6-8" tilapia, 20+ fingerlings in sump tank, lots of great plants, mostly tomatoes