PH pen reservoir mod

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Ok here's a PH pen modification I did a while back -thought I'd post it in case it helps someone out. With these cheap crappy PH pens ( I haven't tried all brands but get the sense they're all pretty fickle ) the main problem I've had is the reservoir tip only holds a tiny bit of buffer solution, and once they dry out they're never the same again. Mine is/was good for a week or maybe two in my room but after that it's dry. Now I really feel no love for this pen and I have a regular graveyard of the damn things but I sure miss it when it's gone! Always have yourself a backup like PH test drops or the paper strips. One of these days I will spring for a real combo meter, which of course I could've paid for by now with all the money I've spent on crappy pens! Lol...
Not sure why I didn't think of this fix sooner than I did. I'm sure someone has but I haven't seen it.

This one not so great picture is pretty self-explanatory or I would have taken more for you but here's what I did:
Found the best container I could around, which in my case was a baby food jar. Not the best. Ideally the container would've been a little bit shorter and smaller plus the lid screws on kind of funny but this is all I could find on hand.
Traced the reservoir outline on the lid, then marked diagonal lines from the corners of outline to the center.
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Cut along those diagonal lines. I used a small chisel and put the lid on a small piece of wood for backing and carefully hammered the chisel down on those lines to cut them. Then with pliers I bent and folded the resulting triangular flaps downwards. Then I slid the reservoir cap in. Mine fit quite tightly. Make sure the pH pen still slides in and out of the cap easily. You may have to adjust it so it's not pinching the pen and making it hard to fit.
I drilled a bunch of holes in the bottom of the cap.
Then I took the cap out, spread a bunch of five-minute epoxy on the relevant areas and slid the cap back in.
Then glued something flat and heavy on the bottom of the jar to make the whole contraption more stable. Even though it was pretty good already. What I stumbled on at the time was an old metal cutting/grinding disc.... Yeah I'm not putting much love into this but I pray it's the last pH pen I will have to suffer with. Not very elegant but you get the idea anyway if you want to make a nicer one.
I filled up the jar with pH 7 buffer solution, screwed the lid on, and I'm good to go. I think now I can safely leave this pH pen for months and I don't have to worry about tipping it over so much.
 
The minor thing I would add to this post is to mention that- after use, if I put the pen back in to the reservoir/lid while it's still in the bottle,fluid tends to squirt out and get wasted. So now instead, I unscrew the lid first and insert the pen and then screw the lid back on.
 
I really like the idea! I'm going to have to make one for myself!

There's a few things I might suggest to make it easier. The first would be to cut off the bottom of the cap to allow faster flow, and also adding another small hole in the lid as an air relief. The second is to fill the meter with a potassium chloride solution (from what I hear) to keep the meter working longer. I'm not sure what concentration this needs to be, but maybe some research into MSDS's of common storage solutions would show it?

Again, great DIY! I currently sit mine in a cup of distilled water, which is probably a no-no..
 
Cutting the end off the cap is a great idea. I'm not sure why I didn't. I think I had some sort of reasoning behind it at the time, lol. I have mine stored in PH7 solution, whatever that is... Yes I think storing it in water is a no no. I'm not sure what potassium chloride is- googling now...
Hmmm... Well that was interesting, but a bit inconclusive. Ok- KCl solution is good for storage. Got a few recipes. Got a bit of a headache. The easiest possibility which sounds like it might be ok is to mix the KCl with distilled water until it's totally saturated. Can't get much more simple than that.
Cool ideas, JoJo. Post pics if you get somewhere with it? I felt bad my version was so crude- I'm sure yours will be nicer!
 
Cutting the end off the cap is a great idea. I'm not sure why I didn't. I think I had some sort of reasoning behind it at the time, lol. I have mine stored in PH7 solution, whatever that is... Yes I think storing it in water is a no no. I'm not sure what potassium chloride is- googling now...
Hmmm... Well that was interesting, but a bit inconclusive. Ok- KCl solution is good for storage. Got a few recipes. Got a bit of a headache. The easiest possibility which sounds like it might be ok is to mix the KCl with distilled water until it's totally saturated. Can't get much more simple than that.
Cool ideas, JoJo. Post pics if you get somewhere with it? I felt bad my version was so crude- I'm sure yours will be nicer!

Yeah, I think storing it in something other than the KCl solution or a pH 4 buffer is a no-no because it will "deplete the hydration layer" or some such science talk. I'd agree with you, that it'd probably be easiest to just store it in a saturated KCl solution.

For those that don't know, you can get KCl in many salt substitutes at the grocery/supermarket, or in giant bags as water softeners. Watch out though, as both of these can contain sodium chloride also/instead.

I'll get around to making one soon, and be sure to post pictures. Hey, prototypes are usually rough!
 
While trying to find this thread, I couldn't remember who started it. Surprise, it was the Weasel! You're everywhere, Mr. MOTM!

Anyway, I finally got around to making a reservoir for the pH pen. I pretty much did the same thing as you, but cut the bottom of the cap off. I'd better put a wide base on it, like you did. Otherwise I'll get clumsy...

I'll also be storing it in the 4.xx pH solution this time!

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The minor thing I would add to this post is to mention that- after use, if I put the pen back in to the reservoir/lid while it's still in the bottle,fluid tends to squirt out and get wasted. So now instead, I unscrew the lid first and insert the pen and then screw the lid back on.

I noticed I was having that problem too, so I drilled a small hole in the top of the lid, as you can see in the small picture. Now the pressure can equalize and problem solved!
 
Wow, this is a great idea, from a long time ago I'm still pretty new to this site. Love all the knowledge and cleverness from people here. :thumb:
 
Hey- glad you guys dug that one up! That was actually one of my very first posts after I joined. Your version looks great JoJo. Mine still sits faithfully on the shelf- awaiting the very unlikely chance I may have to use it again. I've had to top it up a couple times but the ph pen still seems to work (I think...)
 
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