DIY Alkalinity Monitor

[Borat]

I have done everything from the beginning, uploaded stock code , calibrated using DF robot sample code recalibrated using the KH Mon , still gives me 0.0 dkh at the end of the test . The test progress shows the PH value dropping very slowly for example
Step1
PH 8.2
Acid 1
DKH i think 5 i don't remember

Then step 2
PH 8.12
Acid 2
DKH (value)

Till reaching Acid 5 and dkh almost 14 !!

....

Am super frustrated and donno what could damage the PH probe or the whole PH module (Pen & board) however they are reading numbers correctly but out of the test function

am 100 % positive that stirrer wired correctly. But may be the fact that it doesn't do vortex is the reason and PH module is fine .. to many variables to handle but will start with the easier / cheaper one .. (replacing the fan and magnets and magnet bar (but this can be neglected if you my friend @Borat confirmed to me that your original design doesn't do vortex.

Next option is to replace the ph module this will cost some money unfortunately. Here in Egypt these stuff are not cheap at all .

I almost replaced all components except for PH module

If the stirrer bit spins that's enough to mix the acid.. if unsure - slightly increase the time for stirrer.

Dont rush with conclusions about hardware yet.. the ph board is most likely fine - all it does is amplify electric signal.

When you said you calibrated PH probe, what exactly did you do? What kind of calibration fluid are you using and also are you using my calibration code or the df robot library?

 

[Borat]

DF Robot V.1.1

No, rather which PH electrode are you using?

 

[Borat]

I have done everything from the beginning, uploaded stock code , calibrated using DF robot sample code recalibrated using the KH Mon , still gives me 0.0 dkh at the end of the test . The test progress shows the PH value dropping very slowly for example
Step1
PH 8.2
Acid 1
DKH i think 5 i don't remember

Then step 2
PH 8.12
Acid 2
DKH (value)

Till reaching Acid 5 and dkh almost 14 !!

....

Am super frustrated and donno what could damage the PH probe or the whole PH module (Pen & board) however they are reading numbers correctly but out of the test function

am 100 % positive that stirrer wired correctly. But may be the fact that it doesn't do vortex is the reason and PH module is fine .. to many variables to handle but will start with the easier / cheaper one .. (replacing the fan and magnets and magnet bar (but this can be neglected if you my friend @Borat confirmed to me that your original design doesn't do vortex.

Next option is to replace the ph module this will cost some money unfortunately. Here in Egypt these stuff are not cheap at all .

I almost replaced all components except for PH module

For your calibration of PH probe:

- my code does not use any DF robot code, all the code is doing is measuring voltage received from PH probe at PH=4.0 reference solution and at PH =7.0 reference solution and stores those 2 voltage values in EEPROM. Roughly those voltage values should be about 1 volt for PH=4 and about 2volt for PH =7, can you check what's stored in EEPROM after calibration?
- first simple check you should do it check for loose BNC connector: when the PH electrode is disconnected, the board would still give you spurious readings (such as PH 8.0), rather than say that no voltage is detected!
- you say you ran calibration, once you run it - you should be able to check that PH probe gives correct PH reading: take it out of your monitor (keep it connected though) and put it into 4.0 PH reference solution and then check that your monitor gives you 4.0, then do the same for 7.0, if your probe returns ~correct PH in each case, you can eliminate any doubts about DF Robot board and the PH electrode
- lastly check that PH probe is properly submerged in the sample - maybe it's out of water?

 

[BassamKassem]

You should check your acid concentration.. at acid = 5, what kind of PH do you get (just before it gives up)?

the reading gives me + or - 7 i think ph

 

[BassamKassem]

t

No, rather which PH electrode are you using?

The one came with it , its blue glass probe with white top attached to its wire

 

[Borat]

t

The one came with it , its blue glass probe with white top attached to its wire

Thats's a a very cheap and unreliable probe that I normally just throw away... It should still work - but to run alk monitor you need a good probe.

 

[Borat]

People advise to buy Milwaukee double junction probe - it's accurate and lasts for long (and does not cost a fortune). I use Extech Instruments 601500 probe - it's pretty good, but single junction, so may not last as long as Milwaukee.

 

[cliffE]

I did a stir with my square cylinder like you have basaam and compared it to a round cylinder container. Just took a plastic cup and filled with 100cc of water.

Great vortex on the cup with simple stir found in original code

I’ll try it with some sediment in the water to see how it mixes. But the vortex is better with a cylinder and I’m going to change that part in my build.

Mixing May be part of your issue. may need to mix longer.

 

[Borat]

I did a stir with my square cylinder like you have basaam and compared it to a round cylinder container. Just took a plastic cup and filled with 100cc of water.

Great vortex on the cup with simple stir found in original code

I’ll try it with some sediment in the water to see how it mixes. But the vortex is better with a cylinder and I’m going to change that part in my build.

Mixing May be part of your issue. may need to mix longer.

For now - just increase the stir time (by editing the code), where I stir for 3 seconds - stir for 15, it should do the trick..

 

[BassamKassem]

hello @cliffE and @Borat , both of you are such good persons .. I can't thank you enough for your valuable and good advises .. regarding the reaction chamber am going to change it too to be cylinder shape instead of square to have nice and good stirring .. i will replace current PH probe with another one and will keep the current one as spare

After a very nice and long and good sleep . am back to the game

I started all over again from the start

- I 've calibrated my PH using the calibration method within the KH Mon using calibration liquid "Milwaukee" 4.01 & 7.01PH readings were accurate . and now when i remove the Pen from the reaction chamber and put it in another liquid container it reads its PH accurately

- I increased the stir time as recommended however my current relay got burnt out "mistake from me" so i kept the stirrer running during the whole test without stopping till getting new relay tomorrow

- I started a new test ... first thing : there was no warning message related to acid priming = Good sign .

- during the test the PH value was decreasing with good value till reaching PH end point with total acid added less than 5 but i don't remember the number

finally the machine is working now. I will hook it to my tank and enjoy .

This project was hard and amazingly enjoyable despite its cost . since I've burnt a lot of hardware almost all during the making also most of the items are imported . However am supper happy and satisfied with the results .. thank you @Borat for your continuous help and advices and support you are really amazing person ..

for now i will take some rest and will continue the mobile app .. i will also add its document for any one here needs to amend finish what i've started and share it with us .. am using MIT App Invertor for the mobile app . its very easy and self explanatory platform

here are the the notifications .

 

[BassamKassem]

Hello my friend , can you please recommend in of these PH probes

I 've looked for Millawakee and not found here in Egypt .

The yellow one "Adwa" no board included

 

[Borat]

Hello my friend , can you please recommend in of these PH probes

I 've looked for Millawakee and not found here in Egypt .

The yellow one "Adwa" no board included

I know neither of the 2 - but by seaching it seems ADWA is a proper manufacturer of PH probes and also ADWA is a double-junction probe... so my bet would be on ADWA..

Hope this helps.

Cheers,

B.

 

[Borat]

I know neither of the 2 - but by seaching it seems ADWA is a proper manufacturer of PH probes and also ADWA is a double-junction probe... so my bet would be on ADWA..

Hope this helps.

Cheers,

B.

By the way, when people order Millawakee here in the UK - its not available locally, so it is shipped from US for about $15 shipping charge.

 

[BassamKassem]

I know neither of the 2 - but by seaching it seems ADWA is a proper manufacturer of PH probes and also ADWA is a double-junction probe... so my bet would be on ADWA..

Hope this helps.

Cheers,

B.

Long time no questions from me I bought ADWA probe and yes it is amazing , extremely accurate , my question here in earlier post you 've mentioned something about increasing accuracy by diluting HCL and amending its formula . can you walk me through it step by step please .. the reason am asking is .. i initiated a test and its result was 9.29 then after 30 minutes i did another test and its result was 9.12 so I think and i might be wrong if I diluted the acid it would be better .

@Borat

 

[Borat]

You shouldn't really chase precise numbers, DKH readings that are 0.1 apart are pretty good.. However if you want to dilute you 0.1N acid follow this simple instruction:
- let's start with 4x dilution, which is 0.025N acid strength
- mix 100ml of 0.1N acid with 300ml of RO water, this should make it 0.025N solution
- declare a new (global) constant for acid concentration used:
const float ACID_CONCENTRATION = 0.025;
- amend getDKH() function to be more generic
float getDKH(float sample_vol,float acid_vol)
{
return acid_vol/sample_vol*2800.0*ACID_CONCENTRATION;
}
- don't forget to modify this parameter as follows
MAX_ACID_VOLUME_PER_TEST 20

that should do it.. You may want to fine tune the amounts dosed on each step of titration, so as to make the titration a bit quicker, but this is optional..

Cheers,

V.

 

[BassamKassem]

You shouldn't really chase precise numbers, DKH readings that are 0.1 apart are pretty good.. However if you want to dilute you 0.1N acid follow this simple instruction:
- let's start with 4x dilution, which is 0.025N acid strength
- mix 100ml of 0.1N acid with 300ml of RO water, this should make it 0.025N solution
- declare a new (global) constant for acid concentration used:
const float ACID_CONCENTRATION = 0.025;
- amend getDKH() function to be more generic
float getDKH(float sample_vol,float acid_vol)
{
return acid_vol/sample_vol*2800.0*ACID_CONCENTRATION;
}
- don't forget to modify this parameter as follows
MAX_ACID_VOLUME_PER_TEST 20

that should do it.. You may want to fine tune the amounts dosed on each step of titration, so as to make the titration a bit quicker, but this is optional..

Cheers,

V.

Great and super simple steps . I will try it out tom and feedback . Thank you again

 

[BassamKassem]

Good news for those whom wants their devices to connect to available wifi network from your choice not hardcoded SSID and passwords

here is the updated version in which the ESP will search for saved SSID , if not found will switch to access point mode and your will connect to it by opening your wifi from your mobile or laptop and connect to it then it will automatically open a wifi config page inwhich it will ask you to conifg your wifi settings , then you can choose from the available networks and press on save , it will save its credentials and switch back to station mode and connect to the chosen ssid

of course you can add more fields using wifiManager library

 

[BassamKassem]

You shouldn't really chase precise numbers, DKH readings that are 0.1 apart are pretty good.. However if you want to dilute you 0.1N acid follow this simple instruction:
- let's start with 4x dilution, which is 0.025N acid strength
- mix 100ml of 0.1N acid with 300ml of RO water, this should make it 0.025N solution
- declare a new (global) constant for acid concentration used:
const float ACID_CONCENTRATION = 0.025;
- amend getDKH() function to be more generic
float getDKH(float sample_vol,float acid_vol)
{
return acid_vol/sample_vol*2800.0*ACID_CONCENTRATION;
}
- don't forget to modify this parameter as follows
MAX_ACID_VOLUME_PER_TEST 20

that should do it.. You may want to fine tune the amounts dosed on each step of titration, so as to make the titration a bit quicker, but this is optional..

Cheers,

V.

After doing this now results are supper accurate and convenient, benchmarking with other test kits I can confirm that the device is now awesome

Fist test 8.42 / 10AM
2nd 8.44 / 6 PM
Third 8.43 / 12 AM

 

[iLMaRiO]

Just as recap, which dkh accuracy are you able to get and with how much water sample?

 

[Borat]

Just as recap, which dkh accuracy are you able to get and with how much water sample?

0.1 DKH. Water sample 100ml, acid concentration 0.025N.

How to verify accuracy - is simply to re-run the test and compare readings..