# Which TDS/Conductivity meter do you use/recommend?



## Andy Ritter (Nov 26, 2008)

Hello all,

I have been reading a lot of posts that mention using a TDS/conductivity meter to check the aquarium water. However, I don't have one, so I have no idea how my tank water compares. I thought that I might find a thread or two that would give some insight as to the differences between the meters available and recommendations as to which one I should purchase, but I haven't been able to find one. I would like to buy one that is durable, accurate, easy to use, and not extremely expensive. Unfortunately, when I searched for these meters on the internet, I found that there are way too many to choose from. Some are handheld like a pen, some are handheld but with a cable going to the probe, some are continuous monitors with probes for the tank, and some can even have the probes plumbed with the tank water continuously going through them. All of this is way too much for me to think about and gives me a headache. I figured that you guys could give me some insight as to which one to pick. Please let it be known why you like or dislike a particular meter.

Thanks,

Andy


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## rjfurbank (Jan 21, 2008)

I have the HM digital EZ version and like it. I got it for my shrimp tanks and have been pleased with it's performance so far (~6 months). It's very simple and seems durable.

I got mine when I read on another forum that a very experienced shrimp-keeper was using this one--good enough for him--good enough for me.

Good luck!


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## bosmahe1 (May 14, 2005)

Why would you use one, to determine when you need a water change?


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## Zapins (Jul 28, 2004)

bosmahe1 said:


> Why would you use one, to determine when you need a water change?


My thoughts exactly. I'm not sure how a TDS meter would help?


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## ashappard (Jun 3, 2006)

I mainly use mine to monitor TDS on my RODI product

between water changes, I do take a few readings of my aquariums. It is just a ballpark number that increases as I add fertilizer, doesnt tell me what components make it up but it can tell me when I am getting 'buildup' and maybe it will be time for a larger water change soon.


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## TAB (Feb 7, 2009)

TDS meters are a must if you have a RODI.


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## S-KGray (Nov 29, 2008)

I have the HI 98129 Combo meter (measures pH, EC, TDS, Temp). Works very well.


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## bartoli (May 8, 2006)

For a number of years, I have been using the Pinpoint conductivity monitor:

http://www.americanmarineusa.com/conductivityfacts.html

Since I do NOT do water change it is all the more important to monitor water quality. The above monitor tells me how my aquarium maintenance (mostly just feeding fish and trimming plants) have been affecting the water TDS. For example, if I had been feeding too much frozen blood worms or live brine shrimps over a period of time, TDS would slowly build up. Then I held off feeding those food until the TDS reading returned to a better level.

When I bought fish, I always took a TDS reading (along with pH) of the bag water. That helped me to decide how long to drip water into the bag. Even though all the bag water were crystal clear, some of them had TDS above 1,000. Amazing!


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## Jim Lockhart (Jan 27, 2004)

I have the hanna TDS1, the cheapie $13 one , you should be able to find it on Ebay. It works fine for me, it only goes to 999, so that may not work for you. I bought it when I got my RODI unit over 2.5 years ago , and it still works fine. The only issue with it is when the batteries start to go, it gives unexpected readings? It is very easy to use, just ignore the very 1st reading ), which I find is a lower reading than the 2nd and 3rd, which are usually consistent. It's not an issue cause each reading only takes 10-20 secs. I'm sure like anything else you get what you pay for.


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## Andy Ritter (Nov 26, 2008)

bartoli said:


> For a number of years, I have been using the Pinpoint conductivity monitor


I use the Pinpoint pH monitor continuously so I can tell with a glance if the pH (and the CO2 system) are okay. Do you use your conductivity monitor continuously, or do you just check every once in awhile when you want to see how things are going with the TDS? Also, I'm not exactly sure how these monitors work, so is there any possibility that having multiple probes in the water at the same time could interfere with each other (maybe through electrical charges in the water)?

Thanks,

Andy


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## bartoli (May 8, 2006)

I too have the Pinpoint pH monitor. The pH probe and the conductivity probe are together in a tank all the time so that at any time I can instantly get the readings. On several occasions, such instant readings had alerted me to unexpected problem that would not be an issue for people who do water change.

As for interference, I have not noticed any. Based on the little that I had played with the Pinpoint and Milwaukee pH monitor, one can switch probes on a monitor and still get the same reading. Apparently, the key is in how a monitor interprets a probe's signal. Thus, two calibrated pH monitors can give different readings on the same water sample.


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## Andy Ritter (Nov 26, 2008)

First of all, thanks to all of you that have already responded to my request for your opinions on TDS/Conductivity meters.

However, I must admit that considering how many posters that I have seen on APC that mention checking their TDS, that there hasn't been any more responses than this. For instance, I have been using PPS Pro, and there are lots of people that have posted in the Fertilizing Forum that have made mention of using their TDS meters.

I was also expecting to hear some responses such as "Don't buy type A because you have to change part X often, whereas type B doesn't require that". I'm pretty sure that I remember reading where someone said (Edward, maybe?) to not buy a combination ph/TDS meter because the probe has to be replaced every so often. I searched for a long time to see if I could find it again, but had no luck. I figured that there might be some other reasons as to why I should buy one versus another, too.

Unfortunately, this might be one of those questions where if you ask ten different people what they think, that you're going to get ten different answers. The people that have responded so far have basically been that way. I still can't tell if I should buy one of the $15 ones or one of the several hundred dollars ones.

Oh well.  :ear: :? :noidea: :-k :decision:

Thanks,

Andy


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## S-KGray (Nov 29, 2008)

If you are only gonna check TDS then you can get a meter that just does that. I got the HI 98129 because I wanted the versatility to check TDS, pH, temp all at once.


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## bartoli (May 8, 2006)

Andy Ritter said:


> I still can't tell if I should buy one of the $15 ones or one of the several hundred dollars ones.


In addition to not being a continuous monitor, TDS1 displays in PPM. Meters like the Pinpoint monitor displays in microSiemens. See:

http://www.marinedepot.com/controll...oint_conductivity_monitor_information-ap.html

Since 33 microSiemens equal to 17.9ppm, microSiemen display allows one to observe changes at a finer level as well as the propensity of going up or down. Such information can be useful for observing how the minute impact of individual actions done to the tank add up over time.

Ask yourself why you would like to know the water TDS and exactly how you would use that information once it is available.


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