Magnesium deficiency probably due to low ph.

2 gallon pot.

I checked run off after flushing with two gallons of 7.0 water two nights ago and it was 6.0 or below. So I am flushing again tonight this time with 5 gallons 7.0 water and the final runoff is still around 6.0.

Am I missing something?

I'm going to flush with another two gallons but what if that doesn't bring the ph back up? This is not even a 3 week old plant.

The soil is peat moss, pine bark, vermiculite, perlite.