GobyMaster11276
Fish Crazy
Hi, just realised I has a TDS tester that I had never used, and was wondering if someone could give me a simple explanation about it. What should it be at for bettas? Mine is at 134ppm. Thanks.
TDS
- Thread starter GobyMaster11276
- Start date
I cannot explain how a TDS meter works, as I have never used one. I may be able to help with some explanation about TDS and fish (taken from an article I wrote a few years back). This is linked to what I just wrote in response to your other thread on pH.
TDS (total dissolved solids) is basically everything dissolved in the water: chlorine, chloramine, ammonia, phosphate, salt, hard minerals (GH), bicarbonates (KH), organics, 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.
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 impact 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 400 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.
TDS accumulate obviously, so the more water changed regularly, the better. Another reason for substantial weekly water changes.
You specifically asked about Betta; being a soft water fish, the TDS should be as low as possible. The GH has the greatest impact here, so having soft water is a step in the right direction. Then. limiting additives to those absolutely essential. We cannot not use conditioners and risk poisoning the fish with chlorine/chloramine and perhaps heavy metals, but we should attempt to keep TDS low. This is why it is foolish to use more conditioner than needed; manufacturers will still say to dose for the tank volume when changing say 50% of the water, but this is doubling the TDS and affecting the fish, regardless of how "safe" they try to suggest this is for fish. Common sense is a better safeguard.
Byron.
TDS (total dissolved solids) is basically everything dissolved in the water: chlorine, chloramine, ammonia, phosphate, salt, hard minerals (GH), bicarbonates (KH), organics, 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.
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 impact 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 400 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.
TDS accumulate obviously, so the more water changed regularly, the better. Another reason for substantial weekly water changes.
You specifically asked about Betta; being a soft water fish, the TDS should be as low as possible. The GH has the greatest impact here, so having soft water is a step in the right direction. Then. limiting additives to those absolutely essential. We cannot not use conditioners and risk poisoning the fish with chlorine/chloramine and perhaps heavy metals, but we should attempt to keep TDS low. This is why it is foolish to use more conditioner than needed; manufacturers will still say to dose for the tank volume when changing say 50% of the water, but this is doubling the TDS and affecting the fish, regardless of how "safe" they try to suggest this is for fish. Common sense is a better safeguard.
Byron.
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GobyMaster11276
Fish Crazy
So would my TDS be too high?
Pure water does not conduct electricity. Pure water doesn't occur in nature . It is however available and used in industry. A TDS meter is and electrical conductivity meter. It has 2 electrodes and a small amount of current flows between them. The higher the current the greater the level of contaminants. a
The meter is calibrated to a salt of known concentration. So if you put the meter in a calibration fluid of say 400ppm of salt you then adjust the meter to read the same. Some meters have a small screw or knob for the calibration. My Hana meter came with a salt of 1300ppm. I press a button until the display shows cal and then dip it in the solution. it make the reading and assumes you are using the recommended 1300ppm calibration solution and automatically set the meter to that value.
TDS meters are similar to GH meters. WhileGH meters read Calcium and magnesium only. A TDS meter reads everything in the water. So it is possible for a GH test to show zero no calcium or magnesium in the water. while a TDS meter may show 100ppm, indicating a lot of stuff in the water other than calcium and magnesium. So in general a TDS meter will generally read higher than a GH meter. The big advantage of a TDS meter is that you can read the mineral concentration of the water with a resolution of one PPM. For A GH test kit the best that is possible is one degree or 17 ppm.
Calcium is a macro nutrient while magnesium is a trace nutrient for plants. If my plants are growing very well they can ,and on several occasions have, caused my GH reading to drop. A drop in GH might indicate more GH booster should be added.
A TDS reading is however a good way to determine if you are cycling enough water on a regular basis. TDS due to its higher resolution can detect a develo\ping problem (such as nutrient deficiency, over feeding, or the addition of too much fertilizer) faster than a GH test can Idealy you want stable GH and TDS readings..
The meter is calibrated to a salt of known concentration. So if you put the meter in a calibration fluid of say 400ppm of salt you then adjust the meter to read the same. Some meters have a small screw or knob for the calibration. My Hana meter came with a salt of 1300ppm. I press a button until the display shows cal and then dip it in the solution. it make the reading and assumes you are using the recommended 1300ppm calibration solution and automatically set the meter to that value.
TDS meters are similar to GH meters. WhileGH meters read Calcium and magnesium only. A TDS meter reads everything in the water. So it is possible for a GH test to show zero no calcium or magnesium in the water. while a TDS meter may show 100ppm, indicating a lot of stuff in the water other than calcium and magnesium. So in general a TDS meter will generally read higher than a GH meter. The big advantage of a TDS meter is that you can read the mineral concentration of the water with a resolution of one PPM. For A GH test kit the best that is possible is one degree or 17 ppm.
Calcium is a macro nutrient while magnesium is a trace nutrient for plants. If my plants are growing very well they can ,and on several occasions have, caused my GH reading to drop. A drop in GH might indicate more GH booster should be added.
A TDS reading is however a good way to determine if you are cycling enough water on a regular basis. TDS due to its higher resolution can detect a develo\ping problem (such as nutrient deficiency, over feeding, or the addition of too much fertilizer) faster than a GH test can Idealy you want stable GH and TDS readings..
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GobyMaster11276
Fish Crazy
Just wondering, what reading range would classify as 'soft'? Thanks.
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GobyMaster11276
Fish Crazy
Nvm, I just remembered it was less than 100ppm.
Where did you see this? I would question it. To aquarists, the terms "soft" and "hard" refer to mineral content, as measured by GH, and primarily calcium and magnesium. TDS is a measure of all dissolved substances in the water, as I think I previously explained, and to which Steven has added information about measuring with the meter.
My tap water is very soft, the GH is 7 ppm which is less than 1 dGH. This equates with much of the water in the Amazon, as a reference. The TDS however could be higher, due to all the dissolved organics. I don't worry about this, thus I never measure TDS, because I know that the TDS I am adding via conditioners, plant additives and fish food are as low as they could possibly be unless I didn't add these, which would obviously be impossible. Fish must be fed, and water usually must be conditioned. I keep plant additives to the minimum.
When it comes to fish species, I consider the GH and pH of the species. As I have near-zero GH and the pH is on the acidic side due to natural biological processes, I maintain fish that do best in such water. I do significant water changes, 50-60% once a week, to keep accumulations of TDS low. I see no reason for anything more in this regard.
Byron.
@Byron
Some clarification:
Osmosis: Water molecules will move from the side with lower concentration of dissolved substances to the side with higher concentration of dissolved substances.
As StevenF very well explained, TDS is approximated by measuring electric conductivity of the water. This nearly only picks up inorganic ions. Organics have a much lower electric conductivity, therefore will not contribute to the measurement much. Hence TDS is a very poor measure for "pollution" with organics.
Some clarification:
Osmosis: Water molecules will move from the side with lower concentration of dissolved substances to the side with higher concentration of dissolved substances.
As StevenF very well explained, TDS is approximated by measuring electric conductivity of the water. This nearly only picks up inorganic ions. Organics have a much lower electric conductivity, therefore will not contribute to the measurement much. Hence TDS is a very poor measure for "pollution" with organics.
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GobyMaster11276
Fish Crazy
I've not come across specific numbers for TDS that relate to hard or soft water. But as we have been mentioning, both myself and hobby5, soft water in nature will tend to be lower in TDS than hard water, simply because the harder the water the more dissolved minerals. 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.
Byron.
For water GH test:
Very soft is 0ppm.
Soft is 75ppm
hard 150ppm
Very hard is 300ppm
17.9pp =1degree (dH) Note TDS readings will generally be higher than a GH reading. The difference between GH and TDS cannot be predicted. Also TDS readings from two tanks may be different even if the same tap water was used to filled both tanks.
Very soft is 0ppm.
Soft is 75ppm
hard 150ppm
Very hard is 300ppm
17.9pp =1degree (dH) Note TDS readings will generally be higher than a GH reading. The difference between GH and TDS cannot be predicted. Also TDS readings from two tanks may be different even if the same tap water was used to filled both tanks.
TDS is not something I will claim to have much knowledge of at all whatsoever but an interesting thread to read nonetheless.
I have a TDS meter pen and I get between 215 - 260 depending on which tank am testing.
Only find it useful for knowing or researching which fish specie will thrive in my water along with other information I know of my tank water parameters.
Have to say this is not something I test with any regularity at all, just occassionally when i see something may be off with my fish and suspect could be the water and TDS is just one tool I use, so thats about the only time I test TDS.
TDS is more relevent to saltwater aqauriums I think so for the average or new FW hobbiest, its not common knowledge so therefore its something that can be confusing. Even more so when using a test pen or meter thats not accurate or not calibrated properly.
The more accurate information we can get about TDS and what are its uses in the FW aquarium, the better for us all
I have a TDS meter pen and I get between 215 - 260 depending on which tank am testing.
Only find it useful for knowing or researching which fish specie will thrive in my water along with other information I know of my tank water parameters.
Have to say this is not something I test with any regularity at all, just occassionally when i see something may be off with my fish and suspect could be the water and TDS is just one tool I use, so thats about the only time I test TDS.
TDS is more relevent to saltwater aqauriums I think so for the average or new FW hobbiest, its not common knowledge so therefore its something that can be confusing. Even more so when using a test pen or meter thats not accurate or not calibrated properly.
The more accurate information we can get about TDS and what are its uses in the FW aquarium, the better for us all
The more accurate information we can get about TDS and what are its uses in the FW aquarium, the better for us all
One advantage of TDS is that it is fairly fast test. faster than a liquid test. So you could test your water hourly if you wanted to. And it will continue to work as long as the batter is good (it should last months).
The resolution is 1ppm.
For a liquid test you are limited by the amount of chemicals you have and it can take a few minutes to do a test. Additionally GH only tests for calcium and magnesium. it will not detect nitrate, potassium trace metals or organics. So with a GH test you could see the GH value drop as calcium and magnesium are depleted by plants. However at the same time TDS might be increasing due to over fertilization and or a buildup of potassium. Most GH test have a resolution of 17.9ppm. For the strips I use it is 25ppm at the bottom of the scale but 150ppm at the upper end of the scale. So for most GH tests the resolution is typically not enough to see any changes that may be occurring.
So with TDS you can detect:
- If TDS is dropping it means your plants are probably growing and cleaning up the water. No reason for a water change.
- Stable TDS means plant growth is only enough to remove the food waste. A plant nutrient deficiency might be developing.
- A increasing TDS reading could means your tank probably needs a water change due to the following reasons:
- over feeding,
- over fertilization of the water,
- a nutrient efficiency (no plant growth)
- a change in your water source.
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