zeone03

I've got a 20g tank that I have a DIY CO2 using a 2L. My water's ph from the tap is about 8.5. My DIY CO2 drops the ph down to around 7.2. I'll have my plants on Thurs and planned on dosing using the EI method. Would doing a 50% water change and putting water in with a ph of 8.5 and then dropping back down to around 7.2 be too much of a ph swing.

Also I hooked the CO2 up yesturday to make sure I was doing the DIY CO2 right and work, which it is pretty good. I'm using a hagen ladder to disolve it which is does probably 90% (the bubbles shrink to almost nothing by the time they reach the top). Since my plants won't be here until thurs can I just leave the CO2 running or should I take it out until I get the plants?

Thanks
Jason