Saving money on test kits?

[oldsaltman]

Randy, I recently read somewhere that other people are doing their water testing by using the required amounts of saltwater for testing and adding an equal amount of R/O water. Then they double the test results for the final reading. I can see that this would save on chemicals but does it work?
Thanks

 

[Habib]

For most (if not all) titration type of kits you could save reagents by using half the amount of sample and have the amount of reagents and doubeling the end result.

Don't add RO water or so to it because in that case you might still need the same amount of most reagnets or the kit might not function, e.g. in the case of some single reagent kits with several chemicals mixed together.


For color comparison type of kits I would inform with the manufacturers because that can be quite complicated, depending also on how color comparisons are made etc.

 

[Horace]

<a href=showthread.php?s=&postid=7722496#post7722496 target=_blank>Originally posted</a> by Habib
For most (if not all) titration type of kits you could save reagents by using half the amount of sample and have the amount of reagents and doubeling the end result.

Don't add RO water or so to it because in that case you might still need the same amount of most reagnets or the kit might not function, e.g. in the case of some single reagent kits with several chemicals mixed together.


For color comparison type of kits I would inform with the manufacturers because that can be quite complicated, depending also on how color comparisons are made etc.

Will using half the SW and half the reagents while doubling the reading work in the Salifert Ca/Kh test kits?? I do ALOT of testing and it would be nice to save some reagents.

 

[Habib]

Will using half the SW and half the reagents while doubling the reading work in the Salifert Ca/Kh test kits??

Yes, it is mentioned in the instructions how to do that.

 

[Horace]

I will have to try that then and see if I can manage to get a good reading. It seems you would have to be a bit more careful measuring the reagents, especially since how are you going to get exactly half of a "spoon" full accurately?

 

[Habib]

half of a "spoon" full accurately?

That is not critical. You could even use a level spoon or even a one third spoon.

 

[Horace]

<a href=showthread.php?s=&postid=7722802#post7722802 target=_blank>Originally posted</a> by Habib
half of a "spoon" full accurately?

That is not critical. You could even use a level spoon or even a one third spoon.

???

So are you saying that for the Calcium kit, if you add only 3 drops rather than 6 drops of solution, then a full scoop of the other reagent, the kit will still read correctly? Are the spooned in reagents not critical to be in proportion??? I dont understand...Learn me!

 

[Habib]

<a href=showthread.php?s=&postid=7722822#post7722822 target=_blank>Originally posted</a> by Horace
???

So are you saying that for the Calcium kit, if you add only 3 drops rather than 6 drops of solution, then a full scoop of the other reagent, the kit will still read correctly? Are the spooned in reagents not critical to be in proportion??? I dont understand...Learn me!

If you come over, with that question, to the Salifert forum on this board, I will try to explain.

 

[Horace]

Ok, will do

 

[Randy Holmes-Farley]

Just be warned that altering the recipes for test kits often decreases the precision.

 

[oldsaltman]

Randy, that was my original question. If it saves money and chemicals is there a down side and what is it. I don't understand the response?

 

[Randy Holmes-Farley]

Habib points out the reduced precision when using his reduced water volumes recipe with his kits.

Each kit type will respond a little differently, but take an alkalinity kit. If you use half the tank water, you'll use half as much titrant. So there is a savings there.

But each drop will now have a larger range in alkalinity.

So suppose that normally you have:

Drops added to Endpoint .....Alkalinity (meq/L))
0............................................0
1............................................0.2
2............................................0.4
3............................................0.6
4............................................0.8
5............................................1.0
6............................................1.2
7............................................1.4
8............................................1.6
9............................................1.8
10..........................................2.0
11..........................................2.2
12..........................................2.4
13..........................................2.6
14..........................................2.8
15..........................................3.0

Using half as much tank water you will have (after correcting for using half as much):

Drops added to Endpoint .....Alkalinity (meq/L))
0............................................0
1............................................0.4
2............................................0.8
3............................................1.2
4............................................1.6
5............................................2.0
6............................................2.4
7............................................2.8
8............................................3.2
9............................................3.6
10..........................................4.0
11..........................................4.4
12..........................................4.8
13..........................................5.2
14..........................................5.6
15..........................................6.0

So normally you can read alkalinity to +/- 0.2 meq/L, and now using a reduced volume you can only read to +/- 0.4 meq/L

 

[oldsaltman]

Yes, I see the answer now. Sorry I am a little slow sometimes. Thanks again Randy it's great to have you around.....

 

[Randy Holmes-Farley]

You're welcome!

Happy Reefing.