Unfortunately they wont be accurate anymore, three to five years is about it for shelf life. They all pretty much come with expiration dates now, like all things you can fade the date a bit but 10+ years is pushing it. Aquarium Pharmaceuticals (API) have always been OK much better than some of common brands but I far prefer the Sera line of products. I will admit though that that is mostly brand loyalty, at one time they were just about the only firm making really accurate tests...

I like any company that prints the date of manufacture on the bottle just so you know it hasn't been sitting on the store self for years. And I think printing the date on the bottle kind of shows the company cares about getting you the proper product. The date is usually something like a lot number, not really clear.

The other thing I like are companies that have web pages with detailed info about each product, how to use it, etc. Shows they care and the info can be very useful.

In general you can't really just buy the bottles, you need the charts too. They go together. Unless you're sure the new bottles are the same stuff.

Most of the tests last in the 2-4 year range. But that's just a guideline. They can last longer and maybe even less if stored in the sun or something, but I don't really know for sure.

You can test the test kit if you like. Shake them really good for a few minutes if you do decide to use them. If you have ammonia you can put a known amount into a known amount of water and test to see if the test kit is close. For pH you can test vinegar for an acid and put some baking soda in water to test the pH higher range and also KH. Even for new kits if really, really want to make sure the test is good a test against a known solution would be the gold standard.

No harm testing your pond water and seeing what the tests say. I like test results to make sense. Like if KH is 10 ppm and pH says 10 I know something is wrong with one or both tests, or I screwed something up. The tests for chemicals, like ammonia, nitrite, etc, do show lower amounts than actual if they've started going bad so that's an issue.

Or get a new test kits and compare the results with the old kit. If close you know you can use up the old first or toss.

Thanks to both of you. There is just one place still selling the same kit I have, which would be nice since the marked test tubes, which are glass, would be reusable. I can tell from the photo they are the same, so that would leave me with some spares. But no one online gives expiration dates. The newer API kits don't contain as many tests. There is a lot number on each bottle of my old kit, easily readable, and from what I have read online, the dates of manufacture are the last 4 digits, which would range from 08/01-11/01, So I am assuming they are no good. I don't feel comfortable trusting them anyway, Many kits leave out pH, ammonia, GH, and/or even KH and you must buy them separately. But I am concerned that they aren't making this kit any more and I don't want old stuff. I really don't have much available locally. These kits are in the 25.00 range. Other kits are in the 75.00-100.00 range (including the Sera ones available locally) and some even 200.00+. If a 25.00 kit is fine, I don't want to spend 100-200.00+. I don't have an aquarium and I don't keep koi. I just have a 300 gallon water garden with gold fish. But now that that water is clear I can see there are more in there than I thought. I have about 13 fish I think. That is probably a high fish load for the size but they have stayed healthy despite that. With that many fish, though, I want to monitor the water for a while, especially now that it has cleared. Luckily, they seem pretty active and healthy, and I am keeping my old filter going for a good month after I started the new one. I want to try to make sure the new filter is fully functioning before removing the old one. And then I want to monitor the water frequently immediately after removing the old one. If there is an online source where they sell a lot of kits and you know they likely to be fresh with long expiration dates, etc, I would appreciate recommendations, both for complete kits you have used and/or reliable places to get them. Otherwise I guess I will just order and take my chances unless I really need one of those 75-100.00 kits, those I can get locally.

I'm a huge fan of testing.. but that goes back to the aquarium days (as hard as Koi keeping is it isn't a patch on breeding Discus). Testing really does help you learn what is going on in the little artificial environment you have created but I have to admit that other than special situations I rarely test the pond anymore.

I'm trying to think of what I would consider the important tests to have, at least at first...having lots is nice (at least for me) but really Ammonia and pH are the main two I would consider necessary, (test pH first thing in the morning and again late in the day, it will rise over the day the key is by how much). You could easily start with those two and buy others as an when needed, if they are ever needed.

API makes a kit that includes Ammonia, Nitrite, Nitrate, pH and high level pH (a bit redundant) but if you add their hardness test you will have a very thorough little lab. I'm up here in Canada and those two kits would cost me about $50 (horrific sales tax included). Phosphate, copper and Iron are not worth buying unless they are an issue with your water supply. The new API kits have expiry dates on each bottle.

I don't know the details on your filter but 13 goldfish in 300 gallons is not too big a fish load if the filter is adequate. If for example you start to get really high ammonia test readings you can always cut back on how much you are feeding the fish.

My filter is one I just purchased, really for convenience. When I increased the pond size from 150 to 300 gallons the fish load increased also (little devils), and the old filter was no longer keeping up and keeping the pond clear, which I like. So I invested in an Aquascapes (dirty word I now realize, but didn't before I bought it) filter with bioballs and a UV that also has a timer for the UV and a backflow feature to clean it with, that is supposed to be good for ponds up to 1200 gallons. I was looking for something with a UV (although I never had or needed one before), as well a back flow, and smaller filters don't have the back flow for cleaning. Anyway, not returnable once used so I have it. I actually had found in the past by using an old cyprio bioforce foam filter rated for 250-500 gallons, in a 150 gallon pond, my fish were healthy and I had no problems with water clarity even without a UV. But after increasing the pond size and having more fish, I got tired of green water and pulling apart the filter and cleaning the sponges and still not being able to see my fish. After 2 weeks with the new filter the pond is clear for the first time in probably 2 years. But now with the changes to the pond and the new filter and higher fish load I just think I should keep an eye on things for a while. Obviously, I have not been a regular water tester, given the age of my test kit. I have had many years of healthy fish in a stable pond and no disease so I stopped testing.

What about KH? You don't think that is necessary? Just one thing that I could do without, maybe?

Thank you for taking the time to give me your recommendations.

As far as KH is concerned it is measuring the buffering capacity of your water, early in the morning (say just before dawn) your pH will be at it's lowest level of the day. The algae in the pond have spent the hours of darkness taking in O2 and giving off CO2, as the sun comes up that changes. By late afternoon that algae has been producing O2 all day and your pH will have increased. If your KH (carbonate hardness) is adequate that change will be small, large changes can be stressful to your fish and higher pH levels can make "safe" levels of Ammonia and Nitrate toxic. So to a large extent you can get away without a KH test if you test pH "properly" (not 100% but it covers the most important bit).
Doing it this way can also help avoid the pH up & pH down errors many people make.

I'm not familiar with the Aquascapes filters, but the ones I saw when I searched look like the canister type filters we used in aquaria (Fluval was the big brand). If it is that type you can always add a larger biological filter between the Aquascape and the pond.

In the situation you describe, a brand new filter and even a new filter type I would probably add Nitrate and then Nitrite tests.

Nitrate is the end product of the biological filtration, it would be useful to know how quickly it builds up, it will be a good indicator of how well you are doing with water changes.

Nitrite is an intermediate step in the biological process, for me I would be interested in knowing how fast my filter "recovers" from a cleaning, Nitrite levels would help you determine that.

But in both of those cases they are tests that are of interest in a new environment but once you know how your filter is performing they are not something I would be concerned about long term.

Thank you.

I take a different view on KH and pH testing, especially for people who don't test a lot. For people who test a lot they already understand a lot so different tests have a lot more value to them.

pH is a tricky test. As ajames54 said you really have to understand more than many people want to. Like time of day, but there are lots of other things too. I've read more than a few posts over the years where people measure pH and get something off the chart 10+ and freak out. They post what to do, or worst ask a pet store clerk, and someone will tell them to add a pH down product. They add the product and pH is now 6. More freaking out, more chemicals.

Understanding pH Is not something that comes easy to people. It's a complex concept.

The main trouble with testing pH is it only tells you what the pH of the water in the sample at that exact moment in time. But pH can be very dynamic. For example testing the pH of distilled water tells you...nothing. Might be 3,14,7,5 in 4 different tests taken 1 minute apart.

In the hands of someone who knows what they're doing a pH test is certainly very useful. But for people not that into all this it can be a ticking time bomb of bad info.

KH on the other hand tells you a lot more about pH. If KH say is around 5 ppm I know the pH in that pond swings, maybe a lot. It tells me I can't predict what the pH of the pond is going to be tonight or tomorrow or the next day. If KH is say 40-70 ppm I'm pretty sure pH is pretty stable and probably in a very good range. If KH is above say 150 ppm I know pH is very stable and will be stable for weeks to come (in a normal backyard type pond) and I know pH is on the high side, 8-10.

A pond owner keeping pH in the optimal range is going to be an expert pond keeper. They test many water parameters often, maybe daily, and know how to adjust parameters safely. They've probably learned all this the hard way, or they're in the process of learning.

The vast majority of pond keepers have little interest in all that stuff. They want their fish to stay alive and could care less if pH is "optimal" (so the whites on their koi are as perfect as possible or whatever). For them the only thing that should be a concern is stable pH. A pH of 8-10 is fine. Many serious Koi keepers keep their water in that pH range. There is debate on whether keeping pH near 7.4 is really all that important.

So that's why I suggest people start with KH and really don't do pH tests. If it turns out you really enjoy testing water, tracking results, adding stuff to adjust parameters and measuring the result then sure, by all means, get more test kits like pH and have a blast. It is fun, but not for everyone.

Ammonia and nitrite is similar. If you're measuring ammonia on a fairly regular basis it's not really very useful to measure nitrite. If ammonia is 0 every time then nitrite is going to be 0 too. If ammonia is high then nitrite is also probably a problem, or going to be a problem. If this is the first time ammonia has ever been tested and it's high it means the fish have probably been living with this for a long time which means nitrite hasn't been a problem because the fish are still alive. The bottom line is high ammonia should kick off all kinds of actions like finding out why and what to do. That may include testing nitrite. But for most cases fixing the ammonia issue fixes any nitrite threat.

Testing nitrite is useful in specific cases, like high fish loads. Or starting up a pond. Or coming out of winter. But most back yard pond keepers measure nitrite maybe a few times in the summer. That doesn't really tell you much. If you had a nitrite problem the fish would be dead already. When measured a couple of times in the summer the chances of you hitting a window where nitrite was just becoming a problem is low. And of course most backyard pond keepers only test after fish start dying, although many still don't according to posts in forums.

So to me, if I can get a pond keeper to not just test ammonia and KH, but get a basic understanding of why they're testing those things and what to do with the results than they're keeping a pond better than 99.9999% of Water Gardeners and 90% of Koi Pond keepers. Those 2 things cover almost all pond chemistry.

Understanding pH frustrates many people to the point of wondering why they should test at all. Taking pH off the table makes learning what's actually important much more possible. I think people get it if we can just say KH measures the amount of baking soda in your water and you want it to be 150 ppm or more. That they get and may actually do and greatly improve their pond. Of course with the warning only adjust KH when ammonia is zero.

If a person wants to get into testing for pH, nitrite, nitrate, phosphorus, O2, DOC, etc., then super. But very few people want to get into the hobby that deep. And I'm not sure testing all those things really improves anything. I've read posts from people who did this kind of in depth testing and started messing with water parameters and end up with dead fish. That was OK with them because it was a learning experience. I don't think people should get the idea that lots of testing = best home for fish. It's more what you do with the data that matters.

I really want to keep it as simple as possible. I looked but the pet store had no test for KH. It was not in any of the kits. I can order just that test online, which I will probably do. I only want to keep a close eye on things until the new filter is fully functioning and the pond is pretty stable again. You can find my first results in a new post "quick help...", lol. Thank you for all the time you take to explain all this stuff. I did learn about it when I first started the pond, but long forgot most of it from years of not testing at all.