Which pH reading is correct?

[ApheIchthyophobia]

I was using the Tetra Easy Strips (6-in-one test strips) and usually got a reading of about 6.8 to 7, give or take. I also sometimes used a solution (made by API I think - add 3 drops to water in tube, compare to colour chart). The reading I got from this seemed to always be slightly higher, ie 7 to 7.2.

Then when I went to get some more strips, I found the store had run out of the Tetra brand and I got something similar but in another brand (Mardel - never heard of them). When I tested my water about a week later, I discovered to my dismay, a reading somewhere hovering around 5.5. I added a bit of pH Up, tested again...still around 5.5, no change.

Getting suspicious, I tried with my API test solution again, and it appeared to be around 7.2.

So, which is it? 6.8, 7.2, 5.5, or something else altogether? How do we know if we can trust our test strips? Does anyone know if some brands are more reliable than others?

By the way, my fish and plants are thriving, so I suspect it wasn't 5.5.

[Robo-snickers]

go with the reading of the liquid test kit, they are more accurate

[lhenson]

Absolutely go with the liquid! I bought test strips in the beginning, but after a week of double-checking my readings with the lfs readings (they used API liquid) the strips showed me every time that they were not accurate. So, I promptly purchased an API liquid test kit. What is the point of testing at all if you can't trust the results especially when adding buffers. You can go wrong really fast that way.

[Goes to 11!]

Liquid.

Also:

It's a terrible idea to bounce your fish around the pH scale. This is a case where stability rules.
PLEASE quit messing with the buffers, It's even worse if you have no idea what the actual starting pH is.
:22:

[lhenson]

+1 850R !! Just say NO! (to buffers!) thumbs2:

[ApheIchthyophobia]

Thanks everyone! OK, no more messing with buffers, especially with dodgy test strip readings!! I've learned my lesson, although I've only ever added half the recommended dose of buffer at a time.

Mind you, isn't that the purpose of testing the pH? To make sure the water is at a healthy level for fish? And so that you can correct it (gradually) if it's off?

Usually I just use the buffers to get the water to the right pH during water changes, before I add it to the tank. A place I lived previously seemed to have water with a very high pH (like, 8) but now, I check the tap water and it's closer to 7, according to the liquid pH test kit.

All fish still looking happy and healthy, and plants growing and green, so all is good, but I'll use the liquid stuff for pH from now on.

So if the pH reading on the strips is inaccurate, how do I know if it's giving me the correct reading for nitrate, nitrite, hardness, etc?

[Goes to 11!]

Mind you, isn't that the purpose of testing the pH? To make sure the water is at a healthy level for fish? And so that you can correct it (gradually) if it's off?
No.

IMO it is so that I know how much acclimation I need to do when getting stock from out of town but my water is rock solid 7.6pH.

Chemically correcting your pH turns into a lifelong battle that you can never win IMO and all you do is bounce fish around the pH scale.

As I said previously stability is key but if you are always fooling with it trying to get it 'right' the fish have to adjust constantly to it.

Instead, Simply acclimate them one time to your source water and get on with your life. Unless your pH is OFF the scale, Don't fool with it.
Usually I just use the buffers to get the water to the right pH during water changes, before I add it to the tank. A place I lived previously seemed to have water with a very high pH (like, 8) but now, I check the tap water and it's closer to 7, according to the liquid pH test kit.

Check your tap waters pH right out of the tap and then again after it sits 24 & 48 hours. This will give you a base line as to what your pH actually is.

All fish still looking happy and healthy, and plants growing and green, so all is good, but I'll use the liquid stuff for pH from now on.

So if the pH reading on the strips is inaccurate, how do I know if it's giving me the correct reading for nitrate, nitrite, hardness, etc?
You don't & nobody implied they would, We all essentially said 'Use liquid, Test strips are inaccurate'.

Use liquid for all testing.

[ApheIchthyophobia]

Thanks for your reply; that does make sense. I'll reconsider buying those strips and see what they have in the way of liquid testing instead. I only bought them because when I took a water sample from a then-new aquarium to Petsmart for testing, and that is what the employee used and recommended. (I have since discovered a local aquarium shop that's much, much better so I can ask them too).

I took this hobby up just this year after a 30-year hiatus, ie I always had tanks as a kid and in my teens. When I saw all these testing kits in the stores, my thought was, "I don't remember worrying about all this before!!" My next thought was, "But I had a lot more fish dying back then too; not so much now." I somehow figured out back then that you don't just set up a new tank and dump all your fish in at once or they'll die, but the nitrogen cycle was not even on my radar back then. Still learning! Thanks for the info and clarification.

[ApheIchthyophobia]

OK, so I went to the GOOD aquarium shop (it's not in a place I can get to very often) and asked what test kits they recommended. It happens that the guy who REALLY knows planted aquariums and has taken seminars with ADA in Japan, was working that day and I ended up getting a 20-minute lesson in water chemistry, and on plants as well (last time I was there he talked to me for half an hour on plants). This is really a wonderful shop; you walk in and they have beautiful, beautiful planted aquariums in there and every member of their staff is ultra knowledgeable. I ended up buying all liquid test kits. Went home and again got a pH reading of 5.5 with the new kit, while another liquid tester had given me 6.8. So I went back into that shop with a water sample, and they tested it for me using the same brand of testing kit they'd sold me; this time it came out 6.8 and he said my water was just fine. He said sometimes you get a batch that's a little off, and that until this bottle of reagent is finished, I should assume it's about 1 full point off.

[Goes to 11!]

I ended up buying all liquid test kits. Went home and again got a pH reading of 5.5 with the new kit, while another liquid tester had given me 6.8. So I went back into that shop with a water sample, and they tested it for me using the same brand of testing kit they'd sold me; this time it came out 6.8 and he said my water was just fine. He said sometimes you get a batch that's a little off, and that until this bottle of reagent is finished, I should assume it's about 1 full point off.

You are very welcome :22:
Hmm - I am not fond of guestimating:scry: Any chance he will replace the 'batch that is a little off' considering it is certainly not living up to what you intended to purchase.

Two quick questions:

1. [I have to ask this :14:] Is it possible that you did not follow the instructions properly [It does happen] and this is affecting your results?

2. Is it an API test kit? If so, It may be out of date.

Here is how you check:

On every bottle there are digits & the last four are the batch date in a MM/YY format that tells you when it was produced.

The length of time the reagents are good for is as follows:

Ammonia Test Solution # 1 - 3 Years
Ammonia Test Solution # 2 - 3 Years
High Range pH Indicator Solution - 3 Years
Nitrate Test Solution # 1 - 3 Years
Nitrate Test Solution # 2 - 3 years
GH Test Solution - 3 Years
Calcium Test Solution #1 - 3 Years
Calcium Test Solution #2 - 3 Years
Phosphate Test Solution #1 - 3 Years
Phosphate Test Solution #2 - 3 Years
Copper Test Solution - 3 Years
KH Test Solution - 4 Years
Nitrite Test Solution - 4 Years
Fresh Water pH Indicator Solution - 5 Years

Having an accurate test kit is important so I hope something here helps.

:22:

[ApheIchthyophobia]

This is the Nutrafin brand that he sold me. I will have a look at the expiry dates next time I pull it out. The other liquid pH tester I already had on hand (the one that told me 6.8 - 7.0) was API. I was using that to test the pH out of the tap and adjust before I added it to aquariums during water changes, and I was using the strips to dip directly in the aquarium periodically. I knew the strips were giving me a slightly lower reading. And then I got those newer strips that gave me 5.5, which was what prompted this whole confusion and posting here.

I never thought to ask if he'd replace the kit that was supposedly off. I guess the other question I never thought to ask, here or in the store, was about the fact that I have the Fluval substrate for planted aquariums. I'd heard that it lowers the pH, but really, to 5.5??? And is this just in the beginning, or shouldn't it stabilize over time?

Anyway, as I mentioned before, fish and plants are thriving like I've never seen before (aquariums I had as a child were never this healthy) so I guess something's going right.

[Goes to 11!]

I would check the date on your API pH test against my previous post. If it is in date I would use that to test your tank.

One thing I think that is affecting your readings is using two different testing media on two dif water sources and then comparing the results.

You might be off by a bit in opposite[or the same] directions and this could really mess with your results.

I use the same test and read it under the same light for all my tanks so that the only thing that changes is the readings of the test. [I hope that is clear]
I am not sure how long your tank has been cycled and running so it may still be in the 'beginning' know what I mean?

Thriving is an excellent way for plants to be thumbs2: :-D.
:22:

[ApheIchthyophobia]

Yep, I understand. Consistency. Change only one variable at a time. I used to do photo processing and I have a science degree so I should know better than to mix and match testing materials, temperature, lighting, etc., yet...guilty as charged.

I first set up a 20 gallon in February; then in early June I moved, and took the opportunity to move everything into a 45 gallon. The move was chaos and I did not save the filter media and I started from scratch with new water, new substrate, etc. I had about a week's leeway in between homes, so I stuck the plants in, then the zebra danios a few days later, and then after another few days, ALL the rest of the fish. Amazingly enough, no casualties save for one one-eyed baby platy that disappeared a few days after the move. After about 2-3 weeks, I added a couple of corys and some neon tetras. So I'd say the tank's been running about 7 weeks now; I can't say I fully understand all the ins and outs of cycling (I can read up on this for the next one) but it seems to have gone all right regardless.

[Goes to 11!]

Yeah you got it. Sorry, It is late so my faculty for clarity is fading but on a hunch I figured you might understand my inept description because you abbreviate pH correctly. :-P

Nice job moving and all, I would absolutely say this tank is still in the 'beginning' of it's newest incarnation so the substrate might still be a factor in the pH issues.