Very annoying density probe problem

[RDS]

Hi,

my density probe is driving me crazy.

It’s a new probe without rust (all metal bands are absolutely clean!).

The problem: Every day the reading of the probe goes crazy (see attached files - 2 examples of the last two days).

This is what I do: I clean the probe (metal bands) with a piece of paper (kitchen roll) and calibrate it to the real density (e.g. 1023,2 g/L). For 10-15 hours the reading is very accurate and constant (you can see it on the graph).
Then, without any reason, the reading goes up.
After cleaning it with a paper or piece of cloth, the reading is almost down again to the normal value but not exactly (1023,2 --> ~ 1022,7) - but much better than before.

It seems that a kind of (invisible) film builds up over the metal band after some hours which troubles my probe.

Why does my probe have this behaviour?
What can I do? (I didn't have this problem with my old density-probe).

At the moment, the (expensive) probe is useless!

[RDS]

Sorry, here's the image

[ik2vov]

Hi RDS,

it seems after 06:00 the probe become crazy..... Have you a pump or filter that is switched on after 06:00 ?
Do you have old pumps in sump or tank?

Bye

[RDS]

Hi Gilberto,

No, nothing switched on in the morning and no old pumps (no grounding problems). This is only a coincidence because I've cleaned the probe in the evening the day before.

I've got a new idea...to be continued

[RDS]

Hi,

I think I've found the reason for the unstable readings: Ozone!
I work with very little ozone an thought that it would be destroyed completely in my skimmer, but it seems that it isn't (minimal quantities must be residual).
Now I placed it to a 100% ozone free area and up to now the probe delivers stable readings :)

[DaveWC]

That's great that you figured that out, but aren't you concerned that ozone is getting into your system?

[RobbyG]

RDS If you have that much ozone in the water you are running it way too high.

[RDS]

No, I’m using only < 10mg/h Ozone (~ 130 gal.) - you can’t smell it and it has absolutely no effect on algae, corals, invertebrates,…(I have used it quite a long time) --> but it’s enough to trouble the probe. For a short time the ozone is still stable (after the skimmer) in a small area of my pump and in that area I had placed the probe before.

[ik2vov]

Hi RDS, I'm happy you found the reason of the wrong reading.

Using Ozone it's suggested to put some carbon on the top of the skimmer and to direct the water flow from the exit of the skimmer on a little quantity of carbon, this to be 100% safe.

Bye

[redbull99]

I am not convinced that ozone has this effect, others have also experienced this. I would suggest that by moving the probe you reduced electrical interference and it has nothing to do with the ozone. I have had similar erroneous readings and do not run ozone at all. But moving the probe has reduced interference and the readings have remained stable.

Just a thought.

[RobbyG]

Redbull I agree, the salinity probe is a mess. If it's not ozone it's adding strontium or water changes or bad grounding! Who Knows!
I am not happy with mine and I don't think anybody who really is. To me the Salinity probe is the only weakness I have found in the system, I really hope Aquatronica comes out with a replacement soon.

Gilberto is it possible to find out when they might have a replacement model available?

[ik2vov]

I agree with you redbull99,
old pumps can release little currents, these interference generate the error in the value.

Bye

<a href=showthread.php?s=&postid=8816360#post8816360 target=_blank>Originally posted</a> by redbull99
I am not convinced that ozone has this effect, others have also experienced this. I would suggest that by moving the probe you reduced electrical interference and it has nothing to do with the ozone. I have had similar erroneous readings and do not run ozone at all. But moving the probe has reduced interference and the readings have remained stable.

Just a thought.

[ik2vov]

"Gilberto is it possible to find out when they might have a replacement model available?"
No Robert, Aquatronica is making tests on many probes, first they have to select the probe.

Bye

[RDS]

I'm absolutely sure that -in my case- ozone was the problem (don't know if direct or indirect!) and not an interference.
(explanation of "indirect": Perhaps there is something in the water that coats the bands more quickly in the presence of ozone)


Now a stable reading in the ozone free area for 5 days. But since 2 days I've a new problem: starfishes :D ;) I've a lot of small starfishes in my tank and they use it as a "sleeping-place" --> unfortunately, they trouble the measurement (they also "leave something behind" (secretions,...), because after removing the starfish I need to clean the bands to get a correct reading again (only with my fingers - that's enough)).

Conclusion: The probe is very sensitive :(

[RobbyG]

RDS you probably are right it could be the Ozone, but so is Redbull and everyone else who suggest other possibilities, the probe is just too sensitive to any kind of substances in the water and really just ends up being unreliable. I am currently looking at other options such as a pinpoint probe.
Gilberto please let AQ know that this problem is now getting really bad, as the probes get older it gets worst. Nobody is talking about replacements or refunds, we just want to be able to buy another probe that works reliably. I still would have no hesitation about buying or recommending Aquatronica and I don't even hold them responsible for the probe, they got as many things right as one could hope for but now that they have everything just about perfect they need to fix this last problem ASAP.