Test kit replacements

[ineke]

Just wondering how often people are changing their test solutions. As I have a few tanks and test monthly I go through some solutions quite quickly but I have noticed the the PH solution tends to need replacing about 6 monthly -I notice results way out of kilter with what I know the tank should be.

I use API master test kit and find it cheaper to replace the whole kit than it is to buy individual solutions. I store mine in a drawer so it is cool and out of the light.

Does anyone else have this problem ?

Is there a recommended time for replacing solutions?

[CNgo2006]

there should be an expiry date on each bottle..this should be checked before purchase and you may find that some bottles although in the same test kit will have different expiry dates.

[ineke]

I know about the expiry date thanks and mine are well inside that time but I just wondered if once they are opened the use by time reduces? Otherwise I don't understand why I would get wrong readings once they have been opened for sometime? This has happened 3 times now so maybe once they have been opened they may react to O2 getting in?

[jayc]

One of my pet peeves. Why doesn't anyone sell just the test solution?

I don't need another test tube Mr. API, I already have 20 of them!

Just need the test reagents, and sell it to me at a cheaper price. Surely that glass test tube is costing them $5 of the total price.

 

 

 

Back to your problem Ineke.

If the kit is within it's use by date, it shouldn't be a problem. Shouldn't.

Is the test tube clean? Are you applying the correct amount of drops?

I read that holding the bottle at 90degs, vs 45degs will drip different amounts of the reagent. So always hold the bottle 90degs.

There is also the possibility of misreading the colour charts. 

[ineke]

I checked all things, made sure everything was clean. Redid the tests with the original reagent then used the new one and got a completely different reading. I usually get a high ph reading from a tank that should be lower as a sign that things aren't right. It seems to happen in exactly the same way - ph almost to 8 when it should be around 6.4. So new reagent used and sure enough I get the proper reading.

I always rinse my test tubes after use then fill with tank water , empty and refill before each test. I don't just take one reading when this happens I do several to make sure I haven't done something wrong. It's not a huge problem I just wondered if anyone else had an issue. The first few times it happened I didn't think the test could be wrong so thought something in the tank must have changed but I couldn't find anything to give a high reading so as I had a new kit anyway thought to retest and found it to be the older reagent in the fault. Now if a tank gives a sudden high reading I retest with new - I usually have spare ph testers from the kit on hand. Just seems strange that it happens so often as I said about 6 monthly. I guess I could write to API and find out what the life of an open container is.

[Squiggle]

That sounds like a great idea Ineke, find out definitively from the source.

[ineke]

I have sent an email to the UK company and will let you know their answer. They say they will get back to me in 24 hours. :)

[ineke]

apparantly the PH test solution is very stable and should last at least 5 years past the use by date -having said that they still didn't say how long an opened bottle should last. I will have to look into my testing procedure next time I have a problem obviously I must do something wrong occassionally. I have 4 containers of solution so I might just do a test with the same water same tank etc and see if they all read the same.