Grow Mediums ph and tds calibration solution

[natertots]

Hey guys. I am suposed to be getting a ph and ppm meter in mail next day or so. Just noticed it doesnt come with calibration fluid. Havent looked on afn or google yet cause im at work. Can I make something to calibrate my testers to get me semi close until I order some fluid? Im using maxigro and bloom dor nutes and my tap water is 7ish using walmart strips. I wont be able to get fluid till next payday and im brokes. Any help would be awesome. Thanks fuya.

 

[Sauce]

I don't know about making your own. Because it has to read exactly 7.0 and some even need the 4.0 as well. Costs like 10$ or so.

 

[az2000]

Can I make something to calibrate my testers to get me semi close until I order some fluid?

I initially had the same desire to reduce cost. I read the ph of milk is 6.4 to 6.8. My milk seems closer to 6.8. Yours might be closer to 6.4. But, if you don't have anything better to calibrate to, you could use it to calibrate to 6.6 and at least you'd know you're not wildly off. (I used whole milk.).

There are packets of dry calibration powder you mix with distilled water. My meter came with one and I'm still using it. After 5-6 months it's still ph 6.9 (compared to the Blue Labs 7.0 I bought and also use). I have little 1oz plastic containers for salad dressing (to put in a lunch bag). I put a little solution in one of these and use it 5-10 times. (Just so you understand I'm not reusing ph solution for 5-6 months.). Those dry packets were a little inexpensive than liquid calibration solution. But, if you buy a pint of calibration solution, it can be inexpensive too (considering how long it will last, how many 1 oz portions it contains).

The downside to using milk is that, the longer you use it, the more "film" it will leave on the probe, necessitating the use of cleaning solution (an additional expense).

You can put a few drops of tap water in the pen's storage cap and that will be good enough for storage solution until you can buy real Potassium Chloride storage solution. I would rinse and replace the water in the cap each time or it will contribute to film.

Some pens say to never let your probe touch distilled water, that tap is the best. Others say to rinse clean in distilled. I always use tap. I never understood the discrepancy in instructions.

 

[Dr Who]

For pH I would say that proper cleaning, storage and maintenance of the electrode/probe will help a lot. The storage solution is usually saturated KCl, you may be able to buy the salt from a chemists. It needs to have undissolved material at the bottom.

As far as calibration is concerned, as you have already identified, there are some sensible checks that you can make. A routine one is your water supply, and it is a good idea to check it against an independent method as you are doing. In principle, the electrode response should be fixed within a very limited range. In practice this isn't always the case, especially with the less costly equipment. This means that more than one calibration buffer is ideally required. A consideration here is that the usually available ones are pH 4, 7, and 9. 7 is the only one likely to be close to what you are after. I have seen buffers for use in aquaria, in powder form (Proper pH 6.5) which might give you an inexpensive form of buffer at pretty much the pH value that you are looking for. As noted above, if using milk the extra washing required is likely to make the storage solutions more important.

Again, check that you are getting sensible results from time to time with an independent method (colourimetric tests like the one you are using are probably ideal for this).

The relationship between conductivity (what your "ppm" meter will measure), and total dissolved solids (TDS, measured in ppm) depends to some extent on the composition of the solution. However, if you ignore this effect it may be possible to add a carefully weighed quantity of salt into some water and take a reading once it has dissolved. Bearing in mind that ppm is milligrammes per litre (or grammes per tonne) you will need to either weigh out a very small amount, or make a more concentrated solution and dilute it (as accurately as possible) to give solutions in the range that you are wanting to calibrate for. It will be better than nothing, and you can simply take a note of the reading you get with these solutions (rather than adjusting your meter) and compare it against what you think you should have measured to give you an idea of how the meter is performing.

 

[natertots]

Thanks guys. As I was cleaning out my rig (day 8, changing water every week) I noticed it was slimy alittle. Algae yay lol. Im guessing im getting alittle lite threw my pots. Time to break out the paper plates and home next week thete isnt any. Gonna be hard to scrub when full of roots!

 

[natertots]

Got my meters today and I needs help lol. Below is pic if instructions to calibrate it. Now step 1 n 2 is pretty easy to understand. Are 3 and 4 just there to check to make sure its calibrated right? Its an hde pen meter.

 

[az2000]

Are 3 and 4 just there to check to make sure its calibrated right? Its an hde pen meter.

I had the same confusion with my BestDealUSA pen. It came with foil packets for 6.9 and 4.1. If you were regularly testing lower ph liquids, you might calibrate to 4.1. But, since you'll be in the 5.5-6.5 range, it's better to calibrate to the 6.9 solution.

You can use the 4.1 solution to see how well the meter scales to lower values. You could make a mental note that 4.1 reads as 5.3, and therefore a reading of 5.8 might really be 5.6.

If I remember correctly, more expensive pens like the BlueLab will calibrate both solutions.

 

[Dr Who]

There are 2 ways of doing this

1 Adjust the probe as it suggests in the instructions

2 Record both the reading and the true value, make your measurements and apply a correction

It could be tricky to get a feel for how much adjustment of the probe is required to get the correct calibration, and it will only work for a single point calibration. If you have to make an adjustment to get the correct measurement at e.g. pH 7 then measurements at other pH values may be less accurate.

Making an adjustment (plot reading vs true value to calculate the correction factor) certainly isn't convenient, but will save any messing around with the probe (at least until you are comfortable with using it)

 

[natertots]

K got it calibrated I think....but its saying my tap water is 7.8. Now I checked it against milk and it was 6.8 and, checked my ninegar and it was 2.9, and checked some bottled water (noticed it had a ph of 7.7 on label) and it was dead on. Was some fancy water my wife bought cause she thinks its healthier. I think it was just the pretty bottle lol. So you guys think im good? If so my ph was waaaaay off and I need to drop it. When I tested it with strips I was guessing around 7 but the colors are hard for me to distinguish between. Question is do I drop it gradually or all at once. Im useing vinegar.

 

[Bamba]

vinegar will not keep your PH down for long...
Get some good PH up and Downs.
Advance Nuts have some strong ones! the stronger they are the less you use etc etc