I hate test kits!
 

A couple of weeks ago I finished off my Elos DKH test kit. My DKH had been low (according to the Elos kit) so I had been slowly trying to get and keep it up near 9. The only replacement kit we had at the shop was an API so i brought that home and was getting the same lowish reading as the Elos kit. We finally got some Salifert kits in so I grabbed one of those and it tests out at 12.5:surprise: WTF?....Test with the Sali kit again....12.2 :bad-word:...test with the API kit....9....So which kit do I believe?

Welcome to my world dude. If you want to really have fun go spend $200-300 on some electronic monitor and still get conflicting results. Testing is ***awesome***.

Do what i do. NOTHING.

Split the difference, 9-12 is a good number anyways :razz:

Test Kits SUCK!!!!!!!!!!!!!!

Don't know a thing about this API test kit but with the Elos test kits, I've noticed they sometimes do these "corrections" to the instructions, like if one drop is intended to be equal to 100 of something, they might put a sticker over the card (not the detailed instructions) that say it's 75. Probably just coincidence here but 75 is 3/4 of 100 and 9 is 3/4 of 12 ..

I myself am through with Elos test kits. I never really understood the mass appeal of them to begin with, but between having been thrown off by confusing results and those glass test tubes that break just by putting the supplied stopper thing on them (I've broken at least 6 of those tubes just putting that plug on, or taking it off) I now feel totally burned by them.

The test kits I hated the least were Seachem. They come with reference solutions so you can "test your test kit" and can thus have some degree of confidence in your results. But nobody seems to carry them anymore. Oh, if only someone who worked at a LFS could take sympathy on the plight of the test kit abusee's and could look into ordering something better....

J&L now carries Seachem. I've only used their Iodine kit before but I think I might try them next when my current kits run out. http://www.jlaquatics.com/info/397/S...Test+Kits.html

Remember to check for expiration dates as well. After a certain time some of those test kit solutions do get too old and will give you really incorrect readings.

I once compared two Salifert Alkalinity kits with each other. One said my tank was at 6 dkh and the other said 8 dkh. So there are even differences within the same brand...

Problem with taking that approach is.....how much to dose??? I went to RC and snagged the "store use" Salifert dkh kit and will test with all three kits tomorrow morning. I already dosed the tank with stuff(after testing) this morning so dont want that to skew my results.

So what's the over/short that you'll just get a fourth disparate reading? :)

At least with this 9-12 range, you know you don't want to change the amount at all. If it's 9, you don't want to lessen your dose and if it's 12, you don't want to increase your dose. Ergo, don't rock the boat.. whatever you're doing continue to do so until you have an idea what the number really is.

The Salifert should be giving you a reading in meq/l right? I assume when you say 12.5 it really told you a number like 4.46 which is probably somewhere in the vicinity on 0.05 on the syringe?

I know, I was just kidding. I have the exact same problem. Elos says 7 Salifert says 9. I just keep dosing the same amount and it stays at the same level. A serious pain the arse though.

Then again, my corals are happy so I guess that tells the tale.

I think that's key. I think what's more important is the ballpark figures and the week to week trending.

If you really want accurate alkalinity results then you can do what we do in the water treatment industry, use methyl purple indicator and N/50 sulfuric acid to titrate. The N/50 sulfuric acid is very dilute and harmless. Using a 50 ml sample of tank water, add 4-6 drops of methyl purple indicator and add N/50 acid until the color changes from green to purple. Every ml of acid added is 20 ppm of alkalinity, so 6.5 ml = 130 ppm alkalinity (dKH 7.3). A 4 litre container of N/50 sulfuric acid is about $82.00 from Fisher Scientific. That's good for over 600 tests!

I also use an industrial test method for calcium and magnesium. It's 100% accurate and much cheaper in the long run.

The commercial test kits are not very good and very over-priced. Like the commercial liquid calcium and magnesium additives, the mark-up is scandalous.

The one before my last Salifert test kit came with a Alk check solution. Maybe put up a post looking for some.

btw, both my kits check at 7.0dKH with it.

Hmmm
 

I have the API test kit for dKH and Ca and have found them consistently low lately...6-ish and 380-ish. However, when I dose up to a dKH of 9 and Ca of 420 according to the API test the colours are way better in the acropora so I suspect the tests may be correct....I am soooo confused-ish...:lol:

Ok so I tested again this morning....

API 8.5
Salifert 12.5

tested the check solution which is labeled 7.3....

and got 11.5 *wonders if salifert tests the check solution with their test kits*

so if I subtract 4 from my 12.5 reading I get 8.5 which is what the API test reads:neutral:


The second salifert test kit from the shop was off the charts...according to that one my dkh is over 16.


I hate test kits!:neutral:

Does a person have to use a 50ml sample of tank water? Could I use half that and then 2-3 drops of methyl purple and then for every 1/2ml of sulfuric acid the solution is 20ppm of alkalinity? I ask because $97.95 for the 4L acid and $13.85 for 120ml of the dye plus some tax and shipping for +600 tests isnt much of a deal. But getting twice that many would then make the idea start to make sense.

The cost looks like it would be about $130 for 600 tests which means I would get 4.6 tests for every $1 spent. A seachem alkalinity kit is about $18 for 75 tests which is equal to 4.1 tests per $1. Then again most of us only test once a week at most so 600 or so tests would last 12 years... I think this might require a group order.

https://ecat.fishersci.ca/(fw4tt355o...aspx?cid=20639
https://ecat.fishersci.ca/(fw4tt355o...px?cid=3640757

FWIW the only fresh alk kits I've ever had trouble with are Salifert. I've seen Nutrafin kits get wonky after 6 months or so but fresh ones are usually pretty good and the replacement solution is only $3. Never used Elos much, seems to me like it's the same indicator as the Nutrafin at a different concentration.

You'll never know what is up for sure unless you have a standard to check against. If you have a scale that measures grams you can do this:

1L RO/DI + 148g dry sodium carbonate should give you a 140ppm | 2.8 meq/L | 7.8dkh solution.

Get sodium carbonate (washing soda) by picking up some Aquarius pH+ pool stuff at Crappy Tire.