Hydros IV unstable readings

[Reef Puncher]

Does anyone have a hydros IV? I have had mine for about 6 months. i keep thinking that one week it will finally give me consistent readings. but i have not been that fortunate. one day it will read 8.2 dkh the next day it reads 9.5dkh. My hannah, salifert, and red sea backup kits all show stable numbers. I have tried recalibrating the reagent and fill lines and ph probe, 1,987,234 times. (not really but it felt like that).
I have bought over 6 months about 13 bottles of reagent in hopes the reagent was bad. what am i doing wrong? i made sure no air bubbles were in the reagent line.

Should i buy another IV kit? Should i buy another ph probe? is the ph probe the likely culprit?

 

[JeffB418]

Does anyone have a hydros IV? I have had mine for about 6 months. i keep thinking that one week it will finally give me consistent readings. but i have not been that fortunate. one day it will read 8.2 dkh the next day it reads 9.5dkh. My hannah, salifert, and red sea backup kits all show stable numbers. I have tried recalibrating the reagent and fill lines and ph probe, 1,987,234 times. (not really but it felt like that).
I have bought over 6 months about 13 bottles of reagent in hopes the reagent was bad. what am i doing wrong? i made sure no air bubbles were in the reagent line.

Should i buy another IV kit? Should i buy another ph probe? is the ph probe the likely culprit?

Take a look at my suggestions here: https://forum.coralvuehydros.com/threads/iv-x10-setup-suggestions.2072/

Basically the main things to check/verify that cause variability are:
- keep hose lengths as short as possible between the iV and X10
- Place the iV/x10/and reagent bottle around the same height to prevent variability. i like putting the iV to the left of the X10 RIGHT next to it, then the X10, then my reagent bottle to the right. use the 2 closest pumps on the X10 to the iV for reagent and fill, this helps control those critical hose lengths the most. then use one of the further dosing pumps for the drain since that doesn't need to be precise.
- make sure your stir bar is reliability working in the iV
- make sure the drain and fill tubes into the iV are resting tightly on the bottom of the testing vessel
- some have found adding a temperature probe into the iV testing vessel and using that temp sensor with the pH probe in Hydros helps. use this temp probe as well when calibrating the probe in solution
- for the reagent tube, i found that reducing the output diameter of the tube into the test vessel can help alot in reducing swings. I took the end of a plastic pipette and cut it with scissors and then slide it into the reagent tube. this helps stop some of the reagent bleed during testing
- make sure you are using a glass Milwaukee probe, some older iV kits use a plastic green pH probe, they are slow to react to the titration. the glass ones work much better
- make sure your hoses into the dosing heads are secure and no bubbles are being pulled in
- calibrate the pumps using weight not volume. see above link on how to do that
- set your re-test range tight. the iV will rerun a test if there a large jump in test values. setting this tight as possible helps remove those outliers sometimes

 

[Reef Puncher]

wow great response. thanks.
when i get time this weekend i will cut all my hoses shorter, the reagent one is pretty short but the fill and drain lines are pretty long.

for the reagent tube, i found that reducing the output diameter of the tube into the test vessel can help alot in reducing swings. I took the end of a plastic pipette and cut it with scissors and then slide it into the reagent tube. this helps stop some of the reagent bleed during testing

Do you have a picture of this?

i do have the glass ph probe. what does you ph probe 7.0 look like? maybe ill buy better calibration fluid. my mv reading is -15.5mv and is orange. i wonder if thats an issue?


Lastly on the link you say use a scale for calibrating the reagent. what do you mean? when i calibrate it doses slowly into a small 5ml beaker. it usually reads about 2.7ml so i type in 2.7ml. how would weight come into play in that?

 

[JeffB418]

wow great response. thanks.
when i get time this weekend i will cut all my hoses shorter, the reagent one is pretty short but the fill and drain lines are pretty long.

for the reagent tube, i found that reducing the output diameter of the tube into the test vessel can help alot in reducing swings. I took the end of a plastic pipette and cut it with scissors and then slide it into the reagent tube. this helps stop some of the reagent bleed during testing

Do you have a picture of this?

i do have the glass ph probe. what does you ph probe 7.0 look like? maybe ill buy better calibration fluid. my mv reading is -15.5mv and is orange. i wonder if thats an issue?


Lastly on the link you say use a scale for calibrating the reagent. what do you mean? when i calibrate it doses slowly into a small 5ml beaker. it usually reads about 2.7ml so i type in 2.7ml. how would weight come into play in that?

For the pipette, i took one of these and cut off 1' from the end. Then i inserted that into the end of the reagent dip tube inside the tester vessel. it reduces the diameter of the end of the tube.

I wouldnt change your pH probe yet, but make sure to calibrate it at both 7 and 4. 10 isnt needed. 4 is important since titration ends near 4.

For calibration of dosers, using weight for calibration is much more accurate. See below.

Doser Calibration Recommendations:
- USE A SCALE! Biggest thing that can help you get the most accurate results is to use a precision scale and weigh your calibration fluids. I suggest using something like this scale wehre it has a 0.1G resolution: Amazon.com
- When using the scale, for reagent calibration use 1 gram = 1 mL, since the density of reagent is very close to the density of water.
- When using the scale, for calibrating the fill and drain dosers using tank water, you have to know the SG of your salt water to figure out the gram to ml conversion. If your saltwater is 1.025, then take the weight of your calibration sample and divide it by your salinity. IE: (weight of your sample in grams)/(SG of your tank)= volume in mL. Otherwise if you use gram = ml, your calibration will be off!
- Calibration of your reagent is the most important, followed by calibration of the fill doser. Calibration of the drain doser doesn't have to be perfect since it just drains, but it has to be in the ball park so it knows it actually clears the beaker fully.
- When setting up for the first time, you will need to recalibrate your dosers after a few days since the pumps/tubing need to break in. Then make sure to calibrate monthy after to maintain accuracy.

 

[Reef Puncher]

For the pipette, i took one of these and cut off 1' from the end. Then i inserted that into the end of the reagent dip tube inside the tester vessel. it reduces the diameter of the end of the tube.

I wouldnt change your pH probe yet, but make sure to calibrate it at both 7 and 4. 10 isnt needed. 4 is important since titration ends near 4.

For calibration of dosers, using weight for calibration is much more accurate. See below.

Doser Calibration Recommendations:
- USE A SCALE! Biggest thing that can help you get the most accurate results is to use a precision scale and weigh your calibration fluids. I suggest using something like this scale wehre it has a 0.1G resolution: Amazon.com
- When using the scale, for reagent calibration use 1 gram = 1 mL, since the density of reagent is very close to the density of water.
- When using the scale, for calibrating the fill and drain dosers using tank water, you have to know the SG of your salt water to figure out the gram to ml conversion. If your saltwater is 1.025, then take the weight of your calibration sample and divide it by your salinity. IE: (weight of your sample in grams)/(SG of your tank)= volume in mL. Otherwise if you use gram = ml, your calibration will be off!
- Calibration of your reagent is the most important, followed by calibration of the fill doser. Calibration of the drain doser doesn't have to be perfect since it just drains, but it has to be in the ball park so it knows it actually clears the beaker fully.
- When setting up for the first time, you will need to recalibrate your dosers after a few days since the pumps/tubing need to break in. Then make sure to calibrate monthy after to maintain accuracy.

just wanted to report back that its working much better now. There is still a tiny bit of variance, but were talking like 0.05 jumps. before it was like a whole dkh off. i can def work with this now. i cut the reagent line and the fill line alot shorter. I also put the plastic pipette on end of my reagent tube like you said. Those were only two changes i made and one of those seemed to have fixed the issue.

Im very happy because for 6 months i had all but given up on hope thanks so much for the advice.

 

[JeffB418]

just wanted to report back that its working much better now. There is still a tiny bit of variance, but were talking like 0.05 jumps. before it was like a whole dkh off. i can def work with this now. i cut the reagent line and the fill line alot shorter. I also put the plastic pipette on end of my reagent tube like you said. Those were only two changes i made and one of those seemed to have fixed the issue.

Im very happy because for 6 months i had all but given up on hope thanks so much for the advice.

Great to hear! Yeah the iV works great once dialed in... the biggest issue is that it is very touchy to incorrect setup. I think most users have issues because they aren't aware of these key factors in configuration. If it was an "all in one" solution those critical things could be much easier controlled but CV went this path which opens the door. The Maven will be more of a tightly controlled all in one unit which will help with setup issues and avoid the iV/X10 problems.