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Robo-Tank Isolated PH Circuit
#21
Well March 6th has arrived which has got me thinking, maybe I should forget Robo-Tank and try and invent a pause button for the calendar, that would be original and a real game changer. So unfortunately I'm not quite ready to ship today but will be ready for this coming weekend.

I officially have the circuit running on its own and for the first time I'm able to monitor my aquarium. Apparently my tank has a high source of mysterious noise as I've never been able to use my non-isolated Atlas circuit, as soon as probe touches the water the level immediately shots up past 14.0. When I was using mine with only 3.3v pin isolated the pH was showing about 4 and bouncing all over, but now fully isolated its nice and stable to the thousands.

I've already done some 2 point calibrations which works good and just received 3 different buffer solutions so I can test a 3 point calibration.
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#22
Sorry I don't have the pH ready to ship but I'm very close. I want this to be the best it can so the last week I've been putting in a lot of work on all the formulas, especially the temperature compensation. This took a lot of research and a few headaches but I think its finished.

I was blessed to find a formula that compensates based on temperature of calibration solution and sample. Others I found was only using 0.003/C/pH but this should more more accurate overall. Here's a link if anyone is interested.

https://www.hach.com/asset-get.download....7525673904

I was able to replicate their example and then using a mV per pH ratio chart I found I was able to verify it further.

Now I'm adding some last functions, going to do another bunch of different calibrations and it should be ready.
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#23
Nice to have a proper calibration :D
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#24
Now I'm just waiting on a new pH probe, my cheap $6 probe hasn't been doing so good lately so I had to order one before I ship these. Which probe did you end up getting? I got a Milwaukee MA913B/3 double junction.
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#25
Slope dropped rapidly on the $6 probe?
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#26
That has gotten worse, out of acceptable limit now, but the main problem is it's takes a long time to get a reading, I think I caused the issue by putting the probe in my tank too often without isolation. Based on Atlas if the water being measured has stray voltage it can damage the probe so isolation is required to prevent that. Mysteriously my tank has a high level of current flowing through it as the meters go off the charts when I simply touch the water with the probe. After doing this the responsiveness of the probe is horrible, if I move from buffer 4 to 7 it can take an hour to finally get a reading it will stick to, it slowly creeps up 6.432, 6.433, 6.434, etc... until it hits the max. Now I want to do a final 3 point test but having a hard time. When I started with the cheap probe I did do a 4 and 7 calibration that worked perfectly so I'm sure it'll be ok.

I ordered the probe on Amazon last Friday with 2 day shipping and to my surprise it still hasn't shipped, they've never been this slow as this is a Prime item. I hope they ship it tomorrow.
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#27
Ever thought about fitting a groundingpole to your aquarium?
It is Just a metal bar with a wire on it which goes to a grounded outlet.
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#28
When I discovered this I didn't have a probe to ground it and didn't want to sue wire so I left it, didn't matter as I have no need to monitor pH. Might get one now but I would love to know whats causing it lol...
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#29
Just switch off your equipment one by one to see when it goes away, then you know what caused it.

Most likely a pump or heater
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#30
If only it was that easy. Already did that with no luck, all I have in my tank is a heater and temp sensor and I've physically removed them in the past with no luck, that's why it's a mystery.
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#31
Yeah But you use some form of filtration right?
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#32
Yeah I have 2 canister filters but only plastic hoses contacts the water, I've also unplugged those in the past but it doesn't help.
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Current time: 03-19-2019, 03:43 AM