Density Probe

[Hawkey]

Went to bed last night, with the sg reading 1.025 and its been that for the last week. Got up and it read 1.035! I had to rush off to work so couldn't check with my refractor. But i bet its not 1.035.

Has anyone seen spikes on the denisty readings like this? I remember seeing someone post but cannot find it.


Cheers
Paul.

[RobbyG]

Yes, it happens when the probe needs cleaning. Just slip off the Cover and clean the Metal Bands of any collected rust. Don't flex the probe or you will break it. Just rub clean with a piece of cloth till the Bands are shinny again. I find Calibration is almost never needed but cleaning is needed twice per month.

[Hawkey]

Well i held off that day as when i got home it was reading 1.025. However last night i got up in the night and thought i was dreaming! Its was jumping all over the place from 1.011 to 1.076!

So looks like it def needs cleaning! How do you get the plastic sleeve off Robby?

Cheers
Paul.

[jamesdawson]

Twist and pull at the same time.

James

[RobbyG]

Hold the first 1" of the probe body nearest where the cord comes out with your left hand and then hold it about an inch from the opening at the bottom with your right hand. There is a sleeve that will pull away when you pull the probe apart. If you look closely at the side of the probe you can see the seam. Dont flex the probe, Only a slight turning motion may be needed while pulling it apart, but dont bend the probe or it will get damaged.

After opening you will see the four Metal bands, just clean the rust particles off with a damp cloth. Once again being careful not to bend the probe.

[Hawkey]

should i disconnect the probe or is it ok to leave on?
Cheers guys
Paul.

[RobbyG]

You can leave it on.

[RonBuck]

You can leave it on. But it isn't recommended you leave it running out of water for long.

[RDS]

Two weeks ago I got a new density-electrode (my first had a terrible problem with rust).

Unfortunately, I've also a problem with "spikes" now. Today, within 3 hours, my probe jumped from 1023,2 up to ~1038,0 (without any reason). My probe is 100% clean.

[jamesdawson]

I should have said don't bend it while pulling and only twist a little bit to break the seal so you can pull it off.

James

[RobbyG]

Is your ground probe close to the Salinity probe? If you have any stray voltage in the tank the probe will read erratically. I keep my ground probe about 2" from the Salinity probe

<a href=showthread.php?s=&postid=8706695#post8706695 target=_blank>Originally posted</a> by RDS
Two weeks ago I got a new density-electrode (my first had a terrible problem with rust).

Unfortunately, I've also a problem with "spikes" now. Today, within 3 hours, my probe jumped from 1023,2 up to ~1038,0 (without any reason). My probe is 100% clean.

[RDS]

Which "ground probe" do you mean?
My first density probe didn't show such a behaviour.
If there is a stray voltage shouldn't it influence the probe all the time?

[RobbyG]

Do you have a grounding probe in your sump or Tank??
Stray voltage will always effect the probe, but the effect will change depending on numerous things. If you dont have a ground probe, you should. They are about $15 and well worth it.

[Hawkey]

Cleaned my probe today, found some rust tried to get most of it off, but couldn't get it all. Put it back in the tank and perfect back to 1.0253.
thanks for the advice guys.
Paul.

[RobbyG]

I always have a few specs left on mine also. You can use a dremel and a cotton buffing wheel and clean it all off but it's not really necessary. Just make sure you wipe it clean every two weeks and your readings should be constant.

[Hawkey]

Hi Robby, my density probe starting jumping around again. I checked and there is rust build up. I don't have a dremal can i use some wire wool or some else abrasive to get the rust off?

Cheers
Paul.

[catastrofe]

Not trying to hijack, and this may have been answered in another thread, but is AQT working on a "better" probe that won't need to be cleaned as frequently?

:D

[RobbyG]

Salinity probes work by passing a small DC voltage through two metal bands and measuring the the amount of current that travels from one to the other, this gives you the waters Resistance which equates to its salinity. Unfortunately this DC current is the same process behind electrolysis and has the same effect. The bands tend to attract heavy metals in the water, mainly Iron.

Contrary to what was posted by some, I later did some more research on this and found out that yes even the Great PinPoint probes suffers from the same problem, but possibly to a lesser extent. Most people don't leave their salinity probes in 24/7 so they don't get this accumulation very rapidly but people with controllers do. I am not saying that there might not be some form of probe that uses AC voltage to do the salinity measurements but I have not heard of one yet. If anybody knows of such a probe please let me know.

In any case to answer your questions, don't use anything that's abrasive to clean the probe, you will damage it.

I suspect the reason you are seeing so much build up is that you recently did a big water change?? Whenever I do a big water change for the first 2 - 5 days the probe tends to leech out all the free Iron in the new water. I have found that doing small water changes lessens the need for probe cleaning and is also much better for the tank.



<a href=showthread.php?s=&postid=8750739#post8750739 target=_blank>Originally posted</a> by Hawkey
Hi Robby, my density probe starting jumping around again. I checked and there is rust build up. I don't have a dremal can i use some wire wool or some else abrasive to get the rust off?

Cheers
Paul.

[RobbyG]

I hope so, maybe Gilberto can check that out.


<a href=showthread.php?s=&postid=8758425#post8758425 target=_blank>Originally posted</a> by catastrofe
Not trying to hijack, and this may have been answered in another thread, but is AQT working on a "better" probe that won't need to be cleaned as frequently?

:D

[Hawkey]

thanks Robby. Yes i do 5 gallons a week, as i run the Zeovit method on my tank. I know you kinda answer this before but what else can i use apart from tissue to get the rust off?

Appreciate your help
Paul.

[RobbyG]

I use a piece cloth cut from an old white cotton T shirt. Sometimes I dab it in some alcohol to help clean off the rust.

[ik2vov]

<a href=showthread.php?s=&postid=8758658#post8758658 target=_blank>Originally posted</a> by RobbyG
I hope so, maybe Gilberto can check that out.
I know Aquatronica is testing other kind of probes, i don't know when, but there will be another probe.

Bye

[RobbyG]

Every time I answer a post about a probe problem it seems that the problem bounce's back on me :) My salinity probe started jumping all around on Friday. Cleaned it and it still was jumping!
Even when left in 53ms solution it goes 40.2 then 59 etc. going from impossibly low to impossibly high. I unplugged and cleaned the 6 pin connector but that made no difference. Then I noticed a slight yellowing layer on the bands. almost invisible, like a clear Varnish. I could not rub it off with any of my normal methods so I used some wet 400 grit sand paper and gently polished the Bands. So far probe the probe has now been stable in the test fluid but I am going to wait 24 hours before making any judgement.

Interestingly I had just added some Strontium the day before and that is something I have not added in a long time, I did some checking and Strontium is a yellowish metal, that assume that the strontium we add to the tank has any relationship to the metal. Hmmm I wonder, A strontium coating on the probe??

[RDS]

No, pure strontium is extremely reactive with air. But it seems that the probe is very sensitive to layers on the bands.

Why aren't the band not made up of platinum (like the iks probe)? --> shouldn't rust.

Rust in general: Sure, you can clean it but after some time it will destroy the bands because of pitting corrosion.

[wavey]

I have also noticed that the majority of people that experienced this in the UK were fluidizing iron based phosphate removers. Makes sense as they re putting a lot of fines into the aquarium no matter how gently you fluidise the stuff.

I run zeo and do not use any phos removal and only need to wipe the probe with a cloth for it to come up clean and then only every couple of months, certainly dont need to scrub it or anything like that.

[RobbyG]

<a href=showthread.php?s=&postid=8777151#post8777151 target=_blank>Originally posted</a> by RDS
No, pure strontium is extremely reactive with air. But it seems that the probe is very sensitive to layers on the bands.

Why aren't the band not made up of platinum (like the iks probe)? --> shouldn't rust.

Rust in general: Sure, you can clean it but after some time it will destroy the bands because of pitting corrosion.

The probes dont rust. They act like electrolysis plates and attract metals to them. The free iron in you water will be electrolyzed to the bands and then that iron will rust. That's why If you clean off even the most encrusted probe you find no pitting and thats why after a water change you get lots of rust. Still I wish they could find a better solution, because the probe removes necessary trace metals from the water and also is a pain to keep clean.

AQ if your listening, why not just redesign the probe module to reverse the current flow every few minutes, that will keep the bands clean.

[RobbyG]

Well its been about 36 hours and the probe is still very stable.
My conclusion so far, is that Strontium can coat the probe and cause really wild readings. Strontium probably changes it's resistance wildly on contact with air bubles in the water. Next time I add Strontium I am going to document exactly what happens.