New Toy: TDS Meter

[l_l_l]

I was browsing ebay because I recently had a 30$ rebate on it, wondering what to do with the money..
Well..
I found a TDS meter and purchased it.
It is very nice and also came in with a thermometer, makes it so easier to do my water changes! :O

Now, I need to do a lot of reading concerning TDS in aquaria!   

[CAAIndie]

Awesome. If you have any questions about it, don't hesitate to ask. I've been following my tds for quite a while now, and it's a useful tool.

[Sbenson11]

Very cool,

I love new toys.

How is it working for you?

Steve

[l_l_l]

Well, as of today, all I know is that my TDS is perfectly fine for all but one of my tanks, one of them is a bit too high, but this should be resolved fairly fast with a few water changes.

I don't really know the exact science behind all of this but should prove worthy, the more I read about this, the more I learn about water chemistry.

CAA: How do you use your TDS and why is it important to you?

[Sbenson11]

CAA: How do you use your TDS and why is it important to you?

Good question,

Enquirering minds want to know

Steve

[alexmtl]

Just received my TDS meter this week and got around to opening the package and taking a look at it. I got the TDS Meter with a pH meter in the same $18.95 deal. Haven't tried them out but it caught my interest.

[alexmtl]

Well I am measuring most of my tanks at between 140 to 145 ppm. The measure of total dissolved salts (TDS) is a universal collection of all suspended minerals, ions that would carry a charge, and dissolved salts. As a global indicator, TDS gives you a generalized indication of whether your water is hard, ie 200 ppm or soft ie approx 100-150. I think dealing in ranges rather than specific values are better in the case of these cheapo meters (mine for $18.95 for two) since there is variability due to temperature and technique (or whatever).

Not too experienced on why I would want to adjust based upon my dissolved salt measurements at this point as I would rather take carbonates measurements for the type of fish that I keep. As TDS is a measure of suspended particles as well that could impart charges and influence conductivity, I am not sure I would trust this gross measure for soft water fish. Well, certainly open to others experience here.

[l_l_l]

I know that TDS is particularly important when you have fish that prefer acidic water or very basic water. Per exemple, German Blue Rams will prefer acid water, therefore a low TDS (Acid water is almost ALWAYS low in TDS).

The main reason you'd want to monitor your TDS is to know when you are ready for a water change..

In example: My Cherry Shrimp tank should be at around 150. When I see that it is 10+ past that, it is time for a water change.
This will ensure that this environment is stable for them, therefore they should produce more babies for me.

At least, that's what I understood out of it.

[Biulu]

I am surprised to hear that your water sits at 140-150 Alex. I thought the West Island had nice low ranges of about 90?!

[CAAIndie]

Sorry I missed the question until now. I'll give a proper answer tomorrow. In short, I was trying to make a big change in my tank's water (from hard to soft, and a move to an area with a different water supply). It's my quick rough method to try and avoid major shock on the osmoregulation systems of the fish I get (as the lfs is on a different water supply than my tap and my tap is much much different than  the whole tank).

I've attempted to correlate my tds readings roughly to the carbonate and general hardness of the water going into my tank. It's a much quicker way to give me a relatively useful number for mixing tap and reverse osmosis than pulling out the liquid tests every time.

[alexmtl]

I am surprised to hear that your water sits at 140-150 Alex. I thought the West Island had nice low ranges of about 90?!

Yes, here in Beaconsfield the water is sourced from Pointe Claire. Pointe Claire treats the water to be soft. Depending on what they use to soften the water, 140 still is considered soft. I would love to have 90 ppm. Then I can mature into a killi breeder.

Straight from the tap, the water measures 135 to 140. In my tanks, without cuttlebone, between 140 to 150. In tanks with cuttlebone over 150. First, this is a cheapo meter so it is accurate to the limit of its price, and I think ranges rather than accuracy. Secondly, tank substrate probably has a large play in the dissolved salts. I have old stone from 1980 in the tanks which may not be so inert. Adding cuttlebone, coral and shells will affect the measure as well as you know. Well an interesting exercise out of curiosity.

I'm going to start playing with the pH meter now.

[alexmtl]

I am surprised to hear that your water sits at 140-150 Alex. I thought the West Island had nice low ranges of about 90?!

Yes Builu I checked the site and they are claiming 60 to 70 ppm (mg/L). Sounds like killie breeding water. Though I have yet to measure this low, I do not have a high quality TDS meter, let alone a KH meter to accurately read, as the Pointe Claire plant reports in carbonate.
Pointe Claire also monitors free chlorine as well as nitrates so this is reassuring. The test results are published on the website for organic and inorganic testing results.

Hmmm. Have to figure this one out. I would defer to the Pointe Claire tests as they have much more reliable test standards.

[alexmtl]

Sadly the cheap pH meters need to be calibrated. What this means is that you have to have a solution to accurately calibrate against, in the case of pH meters, a buffer solution, preferable two, one at 4, the other at 7. I tried to find household solutions that are accessible that would provide an accurate pH measure consistently and I have yet to find one. Even distilled water at theoretically 7.0 would not have enought ions to make an effective measure. I tried the Biologica Supply house that I usually order from, and even a repeat customer cannot get the buffer solutions shipped as these are restricted.

In summary, I am thinking that pH meters will be good until they lose their calibration. Then you are left with having to find a way to re-align. Even still if you have access to a school or diagnostic lab, you are going to a lot of trouble for a $10 toy. In the end, probably better to stick with the pH solutions test kits. I had thought that I would save money by having a reusable meter but in the end it simply does serve the purpose. Anyone want a pH meter ?

[CAAIndie]

Alex, I bought about an 50  dollar pH meter last year. I know what you are saying about calibration fluid. The one I have suggests you calibrate at 4 and at 7 if you are dealing with water that is slightly acidic, and between 7 and 10 if your water is more basic. My local fish store actually carries these calibration fluids, often in two different sizes. They have small pouches that have enough fluid to do a couple of calibrations (this is all they had in when I originally purchased fluid), and they came in pH levels of 4, 7 and 10. They also normally carry little plastic containers of the fluid as well.  It was suggested that if you are leaving the meter for any length of time, to pour just a tiny bit of the pH 7 fluid into the cap, or even store it dipped in the fluid. If you don't have the pH 7 calibration liquid, pH 4 works too. If you let the meter dry it's a pain, you need to rehydrate the probe in pH 7 fluid for a period of time.

One has to be careful with putting a meter in distilled or even RO water, as it will  ruin the probe of the pH meter. The other problem is the probe doesn't have enough ions to get a reading either. Even if probe damage wasn't an issue, if you were to leave the distilled water or RO water exposed to the air for any time at all, the carbon dioxide in the air will turn to carbonic acid, and give you a slightly acidic pH anyhow (probably 6.8 or 6.9 in my experience). My understanding is you would need to protect freshly made distilled water from CO2 to keep it at 7 exactly.


In short, if you want any of the calibration fluid, I can get it to you. It'll just mean a quick trip to the LFS. You'd probably be best getting the 4 and 7 fluids. How frequently you need to calibrate the meter will definitely depend on quality of the meter, and how it's stored. I found I could keep mine pretty close for about 2 weeks, before I started to see a slightly slip.

I like the meter, but it is a pain. Plus it didn't prove useful for me monitoring the pH of the water I was putting into the tank, as it was nearly pure RO for a time. I pretty much moved to the TDS meter for ease of use, plus it was useful for monitoring the efficiency of the RO filter I'm using. Tangent to that, it looks like I might need a new RO membrane one of these days, I've gone from getting water that was 2 TDS, to about 60 tds. As soon as you see a slip in efficiency of more than 90%, something isn't right.

[alexmtl]

Alex, I bought about a 50  dollar pH meter last year. I know what you are saying about calibration fluid. If you let the meter dry it's a pain, you need to rehydrate the probe in pH 7 fluid for a period of time.

Well considering that I wanted a cheap pH measure that was easy to use, the pH Meter fell short of expectations. I have pH reagent tests as well as the test strips which are cheaper, more readily available and easier to use.

Thanks for the offer, but this was a toy ... not a serious tool that I want to invest in. For you, the $50 version is much more relevent vs my el cheapo.

[CAAIndie]

Alex, I bought about a 50  dollar pH meter last year. I know what you are saying about calibration fluid.  If you let the meter dry it's a pain, you need to rehydrate the probe in pH 7 fluid for a period of time.  

Well considering that I wanted a cheap pH measure that was easy to use, the pH Meter fell short of expectations. I have pH reagent tests as well as the test strips which are cheaper, more readily available and easier to use.

Thanks for the offer, but this was a toy ... not a serious tool that I want to invest in. For you, the $50 version is much more relevent vs my el cheapo.

I figured as much. To be honest, mine just collects dust now.

[Byron Amazonas]

A couple years ago I researched TDS for another forum, and I will just copy the article as it may be of interest in answering a couple earlier question on how this relates.

Total Solids (TSS and TDS) in the Freshwater Aquarium
 
Total Solids basically refers to organic and inorganic matter that is either suspended or dissolved in the aquarium water.
 
Total Suspended Solids (TSS) refers to the amount of solid waste, decaying fish and plant matter, etc. that can be captured and held by a filter.
 
Total Dissolved Solids (TDS) is a measure of the combined content of all inorganic substances contained in the water in molecular, ionized or micro-granular (colloidal sol) suspended form.  Generally the operational definition is that the solids must be small enough to survive filtration through a sieve the size of two micrometer.
 
Fresh water by definition contains no more than 1500 mg/l of TDS.  Brackish water contains 1500-5000 mg/l, and marine (salt) water has more than 5000 mg/l of TDS.  Note that mg/l is basically equal to parts per million (ppm), and also that this is not suggesting a level of 1500 ppm in an aquarium; these are just the approximate figures for the three categories.
 
TDS is connected to GH (general hardness) because like GH, TDS includes the calcium, magnesium and other “hard” mineral ions; these ions are what we measure with our GH test kits.  But water hardness correctly considered is more than this; both GH and KH can affect hardness and TDS levels; however, the reverse is not necessarily true.  Aquarium water can have a high TDS level but a low GH and KH (Jensen, 2009).  The TDS for instance also includes sodium (salt) ions, chemical substances, etc. which are not reflected in the GH.

TDS is basically everything dissolved in the water: chlorine, chloramine, ammonia, phosphate, salt, hard minerals (GH), bicarbonates (KH), etc.  And almost every substance added to the water will increase TDS: water conditioner, fish foods, plant fertilizers, calcareous substances, medications, water adjustment products, etc.

The Effect of TSS and TDS in the Aquarium and on Fish
 
As the above definition indicates, filtration via aquarium filters will (or should) remove the TSS but will not remove any TDS from the water [except, see later on carbon].  While live plants can use some of them, only a partial water change effectively removes the TDS that naturally increase within the aquarium.
 
High concentrations of TDS may reduce water clarity, contribute to a decrease in photosynthesis, combine with toxic compounds and heavy metals, and lead to an increase in water temperature (Jensen, 2009).
 
But the greatest impact, and the one that is not usually apparent to the aquarist until things are too far gone, is the impact on fish.  Hard water fish--as we term those species such as livebearers, rift lake cichlids, and some of the atherinids, cyprinids and catfish—can withstand higher TDS than soft water fish.  The TDS in Lake Tanganyika is around 600 ppm.  Compare this to the near-zero TDS in many Amazonian streams.
 
Fish live in water, and their bodies contain water; the fish’s cells separate these two waters, but the cells are semi-permeable, which means the cell will permit the movement of water and certain non-polar molecules to pass through either way (called osmosis) but will prevent the passage of larger or charged molecules.  The way the water moves is determined by the difference in concentrations between the two waters: water of higher concentration (more dense) will attempt to pass through to the water of lower concentration (less dense) until the two are equal.  If the fish could not somehow control this natural flow, it would either rapidly dehydrate or explode.  But fish are able to control this through osmoregulation, a complex series of chemical processes.  The water moving in or out of the fish’s body will likely have a different pH, so another set of processes controls the function of regulating the pH of the fish’s blood (Muha, 2005).  Both of these processes also affect the ability of the blood to carry oxygen, and this impacts many other functions including digestion, the immune system, and so on.
 
The kidneys primarily work to eliminate excess water, but another function is the conservation and reabsorption of essential salts.  Both processes work to maintain a specific salt/water balance.  This osmoregulation of bodily fluids requires a great amount of metabolic energy.  So a high osmotic pressure (caused by elevated levels of TDS outside the fish’s natural range) will overwhelm the fish with excess water and overwork the kidneys, while a low osmotic pressure (caused by TDS levels below those of the fish’s natural range) will deprive the fish of the water needed for the kidney functions (Evans, 2004).
 
The TDS also affects how fast water moves into the fish via osmosis.  “Pure” water would pass through the fish's cells very quickly, while water with some TDS would move more slowly.  Fish use their kidneys to pump this water out.  The kidneys of fish that occur in hard water don't have to work very hard.  Soft water fish are built by their natural evolution to live in water that they rapidly take in to flush out toxins.  A small tetra will urinate more than three times its body weight every day.  But the higher the TDS, the harder it is for the fish to do this, so the toxins remain longer in their bodies affecting their physiology, causing stress, and this will inevitably lead to a shorter lifespan depending upon species and levels.  This may not be evident to us until the fish just dies, for no “apparent” reason.  Such fish actually become dehydrated, and most suffer kidney problems.  [Geisler (1987) covers the kidney deterioration in cardinal tetra due to hard water calcium with scientific data on the fish’s lifespan directly determined by the TDS of the water.]
 

TDS also directly and significantly impact on osmoregulation occurring in the gills.  When the TDS cause a change in the osmotic pressure, the red blood cells can change shape; a low osmotic pressure will deplete the red blood cells of water, causing them to collapse, and a high osmotic pressure will inundate them with water, causing the cells to expand.  Both results will seriously impact respiration.

How to Measure TDS
 
The GH is one indicator of some TDS, but only the “hard” mineral ions as mentioned previously.  A TDS meter is available, but costly.  Measuring the conductivity [electrical currents passed through the water] will indicate TDS; this is how most ichthyologists, recognizing the tremedous importance of TDS,  measure total hardness in tropical watercourses.
 
For the home aquarist, if water parameters close to those of the fish’s natural habitat can be approximated, this measuring should be unnecessary.  But the TDS meter is gaining interest, especially with those who understand that this test is a more reliable indicator of water quality than both the GH and pH tests [see Jensen, 2009 for more information].
 
How to Deal with TDS
 
Partial water changes; for most aquarists, this will be sufficient, at least to deal with TDS that build up in the aquarium—and over time, continually and constantly, the TDS are increasing day by day.  They enter the aquarium via fish food, water conditioners, plant fertilizers, medications, and any substance that treats water in some way.  Use no more than what is essential, and avoid any that are not.  Obviously this becomes even more important if the TDS of the source water are elevated to begin with.
 
Never add aquarium salt to a freshwater aquarium except as a specific treatment and then only if suited to the fish species; this can send the TDS soaring, further stressing the already stressed fish [more here: http://www.tropicalfishkeeping.com/freshwater-articles/salt-freshwater-aquarium-97842/  ].
 
Brita filters will apparently remove some TDS [I’ve no data on how effective this is].  Carbon filtration is believed by some aquarists to remove some of the TDS, but in planted tanks this is also going to remove much-needed nutrients like DOC (dissolved organic carbon) which are essential to maintain the plants and they can help with TDS.  RO units will remove TDS.  Rainwater is usually safe to use.  Never use bottled drinking water; this likely has more TDS than most tap water.
 
The use of wood, dried leaves and peat also lowers TDS along with the pH.  This also works to keep parasites and (detrimental) bacterial populations low.  Some of the cleanest, healthiest and purest streams in the world are the blackwater watercourses in the tropics.
 
For most of us, maintaining fish suited to our water parameters, or providing by natural methods water parameters close to those preferred by the species, will work fine. 
 

When acclimating new fish, or moving fish from one aquarium to another, TDS [which includes GH] is probably even more important than pH.  What is often termed “pH shock” is now being seen more as “TDS shock.”  Fish have been shown to withstand fairly significant pH shifts when the TDS was low in both waters (Jensen, 2009), something I can attest too from my own experience.  It is the TDS, not the pH, that shocks them.  The effects of shock can be offset by slowing mixing the waters.  And this can be important between your own tanks too, as TDS is unique to each aquarium.

Water Softeners [cited verbatim from Dr. Neale Monks]
 
“Domestic water softeners do not produce soft water in the sense that aquarists mean.  What domestic water softeners do is remove the temporary hardness (such as carbonates) that potentially furs up pipes and heaters by replacing it with permanent hardness (such as chlorides) that does not.  While you can pass this softened water through a reverse-osmosis filter to remove the permanent hardness as well, until you have done so, you shouldn't consider the softened water as being suitable for soft water fish.
 
In fact, aquarists are divided on whether the resulting softened water is safe for keeping fish at all.  The odd balance of minerals in softened water is not typical of any of the environments from which tropical fish are collected.  While the chloride levels are much higher than those soft water fish are adapted to, the levels of carbonate hardness are too low for the health of hard water fishes like Rift Valley cichlids, goldfish, and livebearers.  So the safe approach is not to use it in any aquarium, and instead draw water from the unsoftened drinking water source in the kitchen.”


References:
 
Evans, Mark (2004), “The Ins & Outs of Osmosis,” Tropical Fish Hobbyist, February 2004, pp. 76-84.
 
Geisler, Rolf and Sergio R. Annibal (1987), “Ecology of the Cardinal Tetra, Paracheirodon axelrodi (Pisces, Characoidea), in the River Basin of the Rio Negro, Brazil, as well as Breeding-related Factors,” Tropical Fish Hobbyist, Volume XXXV, No. 12 (August 1987), pp. 66-87.
 
Jensen, Niels (2009), “The Importance of Total Dissolved Solids in the Freshwater Aquarium,” as reposted on PlecoPlanet at http://www.plecoplanet.com/forum/showthread.php?t=3480
 
Loiselle, Paul, “Aquarium Water That is Too Hard,” on FishChannel at: http://www.fishchannel.com/fish-health/freshwater-conditions/too-hard.aspx
 
Monks, Neale (1), “A Practical Approach to Freshwater Aquarium Water Chemistry,” Wet Web Media.
http://www.wetwebmedia.com/fwsubwebindex/fwh2oquality.htm
 
Muha, Laura (2005), “Stress” in “The Skeptical Fishkeeper” column, Tropical Fish Hobbyist, December 2005.
 
“Total Dissolved Solids” entry in Wikipedia online at http://en.wikipedia.org/wiki/Total_dissolved_solids
 
Weitzman, Stanley H., Lisa Palmer, Naercio A. Menezes and John R. Burns (1996), "Maintaining Environmental Conditions Suitable for Tropical and Subtropical Forest-adapted Fishes, Especially the Species of Mimagoniates," Tropical Fish Hobbyist, Volume 44, No. 11, June 1996 (Part One), pp. 184-194 and July 1996 (Part Two), pp. 196-201.
 
Byron Hosking
December, 2012

[CAAIndie]

I only had an opportunity to quickly browse through it Byron, but I certainly am supportive of the growing use of TDS in home aquaria. I would comment that meters can actually be found for quite reasonable prices these days.

[Biulu]

Very interesting! Thank you for posting.

[nyleveiam]

What would be the best (and cheapest) way to measure dissolved solids like metals in my water? It is well water, I know it is hard based on Kh and Gh testing, but I also know that it leaves a black soot like coating on dog water dishes, inside toilet tanks and inside pipes. I was told it is iron ore???? I often worry about what it is doing in my fish tanks OR if it is even large enough to filter out. I got an API copper test but it tests negative.
We apparently do not have much calcium since I don't get the white rim on my filters which really surprises me as most people around here do have high calcium in their water.

[alexmtl]

What would be the best (and cheapest) way to measure dissolved solids like metals in my water?  It is well water, I know it is hard based on Kh and Gh testing, but I also know that it leaves a black soot like coating on dog water dishes, inside toilet tanks and inside pipes.  I was told it is iron ore????  I often worry about what it is doing in my fish tanks OR if it is even large enough to filter out.  I got an API copper test but it tests negative.  
We apparently do not have much calcium since I don't get the white rim on my filters which really surprises me as most people around here do have high calcium in their water.

If you are testing for drinking water and human consumption I would go to a professional water tester and not fool around. They could then direct you to remedies.

As for a test for the aquarium, I do not know of a specific commercial test that would isolate iron and iron chelates. The cheapest way to measure total dissolved solids would be the TDS meter. Most likely not able to filter out unless you treat the water yourself, like RO or a commercial water conditioning system.

[CAAIndie]

I second that. If you are worried about the drinking water, I'd go professional testing for sure. Perhaps even if you are just really curious about the make up of it all.

[l_l_l]

I suggest you read that http://lifehacker.com/5927732/afraid-of-contamination-how-to-test-the-water-in-your-house