I've run Happy Frog many times. It buffers pH pretty well, to such an extent that I think micro-managing soil pH with it is over-kill. I just make sure to keep any inputs between 5.0 and 7.0 pH and let the soil do its thing. Just what's worked for me.
@WallyWhite, per my response on a different thread it sounds like the ph pen might not be accurate. The buffers of a typical medium are designed for accommodating typical tapwater so if you are just putting tap water into the soil, you shouldn't need to adjust, at least not until buffers run down. But when you are adding fertilizers, they often change the pH value. So if you're putting nutrients in the water you do want to check value (with a trustworthy pen, OR a solution). When such an adjustment is needed, you should aim for 6.5 which is right smack dab in the middle of the healthy range of 6.0-7.0 for soil.
When the soil creeps up or down over time, then you can adjust your input to compensate and get a good runoff number. So just like you were doing, (example), if you are getting 7.4 runoff you would do a watering adjusted down to 6.0 and slow pour until it falls below 7 and then think about getting things in there to stabilize (sulfer powder, humic & fulvic acids, gypsum, etc).
IMHO the worst hidden offender of upward drift is the carbonates typically added to municipal water. If you ever want to see it at work, fill a bucket of tap water and adjust it. Check it the next day and if it climbed back up, theres buffering minerals in it.
In conclusion, with your FF soil, avoid the hassle of checking and adjusting if you are just giving plain water.
