I run both of your setups.
More lights is always better, providing you don't burn the plants, (use judgement and look at the plants for burning).
Enough said on that.
As for the Bluelab PH pen.
I agree fully with everything that
@Olderfart has said.
I have the soil ph pen from blue labs.
The pen cost me about $200, without regrets,....its worth its weight in gold for my grows and accuracy.
Having said that, ($200 later), I don't mind spending the extra few dollars to get the O
ICIAL solution.
My arguement is, if the pen should become defective for whatever reason during or after the warranty period.
Bluelabs will probably honnor a replacement in the event that something goes wrong.
Perhaps the final and correct answer is,....
Will other products as Olderfart proposes work,...Most probably...will it damage the pen (don't think so).
Can you save a few $,...for sure.
Is it worth the $ savings,...that is a question only you can answer.
My arguement is that using company made products help with warranties should the need arise.
These companies compete for market share and product reputation ( in other words this very conversation we're having).
If my pen fails, but I've been using their products,...and report back to you that....out of warranty they replaced it.
That says alot, and is free advertising for them. ( especially in a site like this with a nich market ( yeah, you and I).
Just food for thought.
Anything is better than nothing,..but not RO or Especially tap water