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spectrophotometer vs colorimeter
- Thread starter deuce03
- Start date
First of all, welcome to RDO, deuce03.
spectrophotometer is in the price range of several grants, and you will really need to be very serious to invest in this gadget. Colorimeter is usually not as expensive, but unless you do a lot of water quality monitoring, I still feel it is overkill.
Before answering your question, may I ask what type of water quality monitoring you intending to do, and at what frequence? In addition, does it matter for batch monitoring or inline monitoring? Did you look into electrochemical instrumentations (such as conductivity, salinity, pH, ISE, etc.)? Is it freshwater or seawater?
spectrophotometer is in the price range of several grants, and you will really need to be very serious to invest in this gadget. Colorimeter is usually not as expensive, but unless you do a lot of water quality monitoring, I still feel it is overkill.
Before answering your question, may I ask what type of water quality monitoring you intending to do, and at what frequence? In addition, does it matter for batch monitoring or inline monitoring? Did you look into electrochemical instrumentations (such as conductivity, salinity, pH, ISE, etc.)? Is it freshwater or seawater?
Fatal Morgana - first, thanks for the welcome and for taking the time to reply to my questions. I agree, the up-front investment for either instrument is not a small $ amount. Several websites do seem to have quality instruments than can be purchased for around $2K. I currently maintain 8 aquariums, 4 marine, 4 freshwater, but they do seem to have a way of just appearing around the house. The intent of the purchase would be two-fold: monitoring water quality of personally owned tanks and also for monitoring water quality of tanks owned by others if motivation overtakes me and a part-time aquarium maintenance business develops. The instrument seems like it might be a good insurance policy considering the nearly $10K already invested in my main reef tank. Having such an instrument may also provide a competitive advantage over other maintenance businesses lacking the capability to provide such flexible, precise and accurate monitoring. Having said that, yes, monitoring would be on a batch basis, rather than inline. Alkalinity, Ammonia-Nitrogen, Chlorine, Copper, Hardness, Nitrate-Nitrogen, pH, Phosphates, etc. would surely be routinely measured. The flexibility to purchase a reagent sytem for nearly any test factor when needed seems appealing to me. However, given the investment cost, and not being an impulse buyer, this forum seemed an ideal place to put the feelers out to a huge knowledge base, see what feedback was provided, and take things from there. Hope that helps.
I see. Here is my two cents worth:
Some of the parameters should be done with electrochemical instrumentation. Salinity/conductivity/TDS/resistivity: get a decent, professional grade instrument. The ability to monitor the water (topoff, RO/DI, seawater, etc.) will let you trouble shoot issue with ionic contaminants going into aquarium on day-to-day basis. Make sure you get one that can work across the whole range from RO/DI to seawater. You will be looking at around $500-$1200 for a professional meter like this.
pH and its evil twin brother, ORP can also be done electrochemically. Some of the conductivity meter on the market usually do both in addition to temperature.
You may want to look into ISE, but in most cases, the sensor is not going to work well in seawater environment.
The rest of the parameters are usually measured with colorimetric method or titration. An auto-titrator will cost you anywhere between $500 to a few grands, which colorimeter about the same. This is in addition to the reagent, and the hassle of calibration, and for batch process, it is usually not going to give you much advantage. However, if you are color-blind or have issue with eye sight, then a colorimeter will enable you to work better. I, for example, can't really tell the difference between blue and purple, but I can read spectrogram and tell you what color the chart indicates.
Keep in mind that three things determine how good a measurement is. 1, The quality of reagent, 2, the technique/methodolgy, and3, the readout/instrumentation. The instrument like the spectrophotometer and colorimeter only help you with the third issue, and it is not going to help you much if you use inferior reagent, improper labware, or practice poor analytical technique.
In summary, IMHO, you be better off if you invest you money on the electrochemical instrumentation, such as a 7 functions water meter (TDS/conductivity/resistivity/pH/ORP/temperature) Well, there is only six... anyway, I feel that it is not going to worth the money if you get a colorimeter unless you nail the technique so well that there is no other limiting factors. Spectro- and colorimeter also give a false sense of accuracy, and many people, even seasoned lab technicians, make wrong conclusion due to this issue.
If I need to go to JFK airport from Manhattan, I won't be impressed by taxi driver driving me there with a Posche. Just get me there safely, on time, and be courteous. Same for aquarium maintenance business. Service is what count, not that you can tell me my nitrate is at 987 ppb.
Some of the parameters should be done with electrochemical instrumentation. Salinity/conductivity/TDS/resistivity: get a decent, professional grade instrument. The ability to monitor the water (topoff, RO/DI, seawater, etc.) will let you trouble shoot issue with ionic contaminants going into aquarium on day-to-day basis. Make sure you get one that can work across the whole range from RO/DI to seawater. You will be looking at around $500-$1200 for a professional meter like this.
pH and its evil twin brother, ORP can also be done electrochemically. Some of the conductivity meter on the market usually do both in addition to temperature.
You may want to look into ISE, but in most cases, the sensor is not going to work well in seawater environment.
The rest of the parameters are usually measured with colorimetric method or titration. An auto-titrator will cost you anywhere between $500 to a few grands, which colorimeter about the same. This is in addition to the reagent, and the hassle of calibration, and for batch process, it is usually not going to give you much advantage. However, if you are color-blind or have issue with eye sight, then a colorimeter will enable you to work better. I, for example, can't really tell the difference between blue and purple, but I can read spectrogram and tell you what color the chart indicates.
Keep in mind that three things determine how good a measurement is. 1, The quality of reagent, 2, the technique/methodolgy, and3, the readout/instrumentation. The instrument like the spectrophotometer and colorimeter only help you with the third issue, and it is not going to help you much if you use inferior reagent, improper labware, or practice poor analytical technique.
In summary, IMHO, you be better off if you invest you money on the electrochemical instrumentation, such as a 7 functions water meter (TDS/conductivity/resistivity/pH/ORP/temperature) Well, there is only six... anyway, I feel that it is not going to worth the money if you get a colorimeter unless you nail the technique so well that there is no other limiting factors. Spectro- and colorimeter also give a false sense of accuracy, and many people, even seasoned lab technicians, make wrong conclusion due to this issue.
If I need to go to JFK airport from Manhattan, I won't be impressed by taxi driver driving me there with a Posche. Just get me there safely, on time, and be courteous. Same for aquarium maintenance business. Service is what count, not that you can tell me my nitrate is at 987 ppb.
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