Can this happen?

[wengdragon]

i usually use Mardel 5 in 1 test stripto test my water. The result is like
NO3 40ppm
NO2 0ppm
Hardness 25ppm
Buffering Capacity 300ppm+
ph8.4
However The Company said in their user guide that if you have a buffering capacity that is too high you can'thave a right reading on ph. Base on that i have drift wood in the tank that my water should be acidic (at lease that is what i think)
However today i use the ph test kit made by Aquarium pharmaceuticals i got the result that my tank water's ph is about 7.2!!!
so here are my questions:
1. How exactly are these ph testing kits work? one thing i know is that our water has iron in it, can that effect the result of the ph test. Can both companies' product sgive me the false reading?
2. if the test kits didn't lie to me, how to lower the ph once and for all? will adding those ph down product fluctuate the ph too much?
Thanks for any answers

[ScottoMacD]

Hi.

I was using those strips daily at the store to test the sumps of our freshwater systems. 5 sumps total. Goldfish, African cichlids, The sewer (predators) Tetra pod CA/SA cichlids.

I would use the strips Monday through Thursday then test with a liquid tester on Friday. Over time I was noticing more and more that the strips were becoming unreliable as they got older. The kicker was when the strips were saying that all of our PH's were out of wack.

While everyone was panicing I retested using the liquid and found that all was normal. It seems that the strips tend to get contaminated very easily. I quess from when you open it and place your hand in the container. I really am not sure though. Could very easily be the amount of humdiity in the air???

First sign is when the alkilinity starts to show 2 colors one round one in the middle and another on the rest of the blotter. Then slowly the others start to do the same.

The only blotter that I have found tended to be relaible was the NO3 (most times than not it was close or very close) the rest were usually off. Sometime slightly other times vastly.

So.

Before getting worried. Bring your water into your LFS for testing. See what they say. Or if you have the liquid tests, retest the rest yourself.

Then make your judgement from there. I have a feeling that you may not be in as rough situation as those strips are telling you.

Good Luck.

Plese post the Liquid results. I am curious to know the final outcome.

[wengdragon]

sorry i forgot to tell everybody that the aquarium pharmacetical's ph test kit is a liquid test solution. when i was useing strip i never care about what it say about ph. i also test my tab water and find out the ph is 7.2 to7.6. i'm more worry about the accurate the test (both liquid and strip) really is and can anything in the water (iron, whatever ion is in the tab water) give me a false reading.
Base on what Mr. ScottoMacD said there is no mistake about the 7.2 reading. if that is the case, how can a tank with drift wood has alkiline water? How should i lower the ph? if those chemicals are the final answer to the high ph will it fluctuate contantly? those are the answer i wish to know.

but anyway, thanks for your help ScottoMacD.

Chris
ps ohhh..... i almost forgot that i just change water yesterday, will it affect the test as well?

[ScottoMacD]

Hi.

7.2 is almost netrual. Not really alkiline

Sometimes the hot water out of the tap will give a higher reading until it cools.

One easy method to lower ph is to place peat moss in your filter. It will lower the ph gradually. Just keep in mind when you are doing water changes that the ph in the tank will rise a bit depending on the amount of water being removed and replaced.

Why do you need the ph lowered? Neutral water is fine for most fish. Are you going with discus or cardinals etc?

Here's a pretty good link on PH

http://www.thetropicaltank.co.uk/ph.htm

And one on water hardness and its effects on ph

http://www.aquariumpharm.com/articles/gh-kh.asp

[boyohboy]

Originally posted by wengdragon

so here are my questions:
1. How exactly are these ph testing kits work? one thing i know is that our water has iron in it, can that effect the result of the ph test. Can both companies' product sgive me the false reading?
2. if the test kits didn't lie to me, how to lower the ph once and for all? will adding those ph down product fluctuate the ph too much?
Thanks for any answers

From a somewhat more scientific perspective for Q1...
1) pH meters actually work by measuring electrical current I believe. As for pH testing solution/strips, they are simply certain chemicals that change color from one to another at a certain pH (range). For example, potassium permanganate change from colorless to dark purple, or bromophenol blue changes from yellow to blue. The pH test strips are simply made by "sticking" these chemical on some sort of (paper) support. The problem with consumer level pH strips is that they'r cheaply made and the chemicals are only loosely bound to the support. The chemical can (and will) become loose and may actually affect the pH ITSELF. This becomes more important as the sample (tank water) volume is very small (only a drop of water on the strip) thus becomes more easily affected. That's why you'll see 2 color range (center and surrounding of water drop has different colors) sometimes. In research lab, we have pH strips (tho rarely use them) that are made by covalently binding the chemicals to the support, thus making the strips more stable and accurate.

Keep these strips dry and dont' touch with ur bare hands, for (abit) more accuracy. I doubt if any level of iron in drinking water will affect the color of those pH test. It's more likely the buffering ions that's affecting the pH result, as stated in ur pH strip manual. If I were to bet, I'd say the pH solution test u had is more accurate. just my 0.02 tho.