Anyone have a good replacement for the old API glass test tubes with caps?

JCinPA · May 7, 2026

They are all the plastic with flip caps now, which work, but I'd prefer glass. Even looking on eBay the old API marked glass tubes are unobtanium, they are only listed at scam sites. Amazon lists them but I've ordered them twice and thought it specifies glass, I got the plastic ones, which I returned. Others have, too. So I'm aware they are listed there, but the are not glass.

I thought it would be easy to find flat bottom calibrated small test tubes with caps, but it is not. All are round or cone shaped bottoms. It's kind of silly of me since the plastic ones work, but if anyone has a source of glass tubes that have flat bottoms, caps and are graduated, I'd appreciate a link! Thanks!

MattW · May 7, 2026

A couple sellers here still stock glass packs of 5. The price has gone up however! I got 6 for £6 2 years ago. This 5-pack is now £9! They also do 24 packs of the plastic ones. Must be phasing out the glass tubes

JCinPA · May 7, 2026

Thank you @MattW They are not "phasing them out" they're gone. I saw an eBay listing in Europe but they don't ship to the U.S. I've given up on finding those at any price. That's why I'm looking for a flat-bottomed, calibrated replacement, but I have not found one yet. I think I'm going to be stuck with the plastic. Which is OK, they do work, and they're cheap. I'd just prefer glass.

Well, slight correction. I've seen some on eBay but without the 5 ml mark on them, they are unmarked, which makes them pretty much useless.

JCinPA · May 7, 2026

Well, speak of the devil! My search fu must be weak. Found them on eBay in the U.S. with free shipping. There are 9 left if anyone else here is interested.

https://www.ebay.com/itm/147174567244?_skw=api+test+tubes&itmmeta=01KR1DJ3GS4MC5QBDVEWJ78CN2&hash=item224449ad4c:g:m5YAAeSwGHdpoOdu&itmprp=enc%3AAQALAAAA8LB2JXbe%2Bh2pdWBqbR2c2Dur61w8DBur3%2FGpg5c5HPoQJHppmNQqbNz1R5rmg7nbpzPFg2vZe4VFp2cWVy6CsN1ppJATJmhGGGL56SC70j2TgdXNxQkHNet6v3SSuI%2BF4Tez1kGp%2F8dtOqQ8Hia%2FmxTDgzhQE3rUWyU6ANjaD61PSI%2FySqithUU8yEw8Nr2R9AEramycSOXQsw%2BMzqVi7TyWQo7b9LmKLQjIoGjxdeZjMFqCpYztP5%2FP4RkGNkjIN0D6gcPqev2TSXJGdORkf6bVgrN7koLKi8WWjUqnRx3Y4gpGczMkMX%2BHhuuGcIa1uA%3D%3D%7Ctkp%3ABFBMyLjIrcBn

They are actually fairly readily available, I must have been on a foreign eBay site, my bad!

Essjay · May 7, 2026

Just to warn you - my experience with the glass tubes is that if not held correctly when shaken they leak. I have to hold mine with my thumb on the cap and finger on the bottom of the tube and squeeze.
I have no idea what the plastic tubes are like, but nitrite test in a glass tube needs to washed immediately after reading the result or a blue layer builds up on the glass which interferes with the test next time.

JCinPA · May 7, 2026

Thanks for that information! This was silly, the plastic ones are just fine, and cheap. But I wanted the glass. I'll keep pressure on the cap and rinse quickly.

Uberhoust · May 7, 2026

There are many test tubes of all sorts of sizes with rubber and cork stoppers available on amazon. I use a syringe to load my tubes with 5 ml of water anyways, so you really don't need the marks on the side of the test tubes.

JCinPA · May 7, 2026

I know that, but the marks are VERY convenient. I found some API tubes and ordered them, so the thread really has no use any longer. Thanks for the inputs!

AJ356 · May 7, 2026

Essjay said:
Just to warn you - my experience with the glass tubes is that if not held correctly when shaken they leak. I have to hold mine with my thumb on the cap and finger on the bottom of the tube and squeeze.
I have no idea what the plastic tubes are like, but nitrite test in a glass tube needs to washed immediately after reading the result or a blue layer builds up on the glass which interferes with the test next time.

Very good point. I'm convinced it's one of the reasons so many people have a false positive ammonia result with API, in terms of Nitrite test contaminating the glass if not rinsed right away. In fact, best to only use Nitrite in one vial and nothing else for that vial.

JCinPA · May 7, 2026

Hmmmm. Interesting. I may get a rack and keep them in order after reading these.

AJ356 · May 7, 2026

Like you, I don't like the plastic tubes. I have been ordering the API spares, but I think they are too expensive. I have a lot of tanks and am a testing geek, love this part of the hobby.

So, I ended up looking on Amazon. I saw some 5ml vials, but I was thinking they don't give enough "space" to shake the liquid, like the API vials.

So, I found 10ml glass vials.

The problem being, I don't like all the writing on the glass, would rather have one line that indicates 5ml level.

However, if you look at what I ordered below, you can fill the vial to 5ml and then just turn it around so you don't have to look at the writing. I've not tested them yet

Nadisean 20Pcs 10ml (1/3 Oz) Clear Glass Vials with White Screwcaps, Small Glass Sample Vials, Borosilicate Glass Graduated Liquid Sampling Sample with Funnels Labels for Solid Liquid Powder Storage : Amazon.co.uk: Business, Industry & Science

Buy Nadisean 20Pcs 10ml (1/3 Oz) Clear Glass Vials with White Screwcaps, Small Glass Sample Vials, Borosilicate Glass Graduated Liquid Sampling Sample with Funnels Labels for Solid Liquid Powder Storage at Amazon UK. Free delivery on eligible orders.

www.amazon.co.uk

WhistlingBadger · May 7, 2026

Interesting. I vastly prefer the plastic ones with the build in lids. I like the glass tubes OK, but the push-on plastic lids were awful. I've actually had a couple of the tubes break under the pressure of getting the cap on or off.

Boundava · May 7, 2026

JCinPA said:
They are all the plastic with flip caps now, which work, but I'd prefer glass. Even looking on eBay the old API marked glass tubes are unobtanium, they are only listed at scam sites. Amazon lists them but I've ordered them twice and thought it specifies glass, I got the plastic ones, which I returned. Others have, too. So I'm aware they are listed there, but the are not glass.

I thought it would be easy to find flat bottom calibrated small test tubes with caps, but it is not. All are round or cone shaped bottoms. It's kind of silly of me since the plastic ones work, but if anyone has a source of glass tubes that have flat bottoms, caps and are graduated, I'd appreciate a link! Thanks!

Not API but a quick search for glass tubes on Amazon yields results. this one is nice as it has the plastic cap but also a stopper.

Amazon.com