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Latro 10-26-2009 06:53 PM

KH seems low--why, and should I care?
Tank parameters:
55 gallon
Source is tapwater conditioned with AquaSafe
Most recent test parameters:
60-80 ppm nitrate (my kit makes it hard to tell the difference on the nitrate scale)
0 ppm nitrite, ammonia, chlorine
300+ ppm GH
~40 ppm carbonate
pH ~6.6
(these are from a Jungle Laboratories strip kit; I also have an API drop kit that I don't use much due to it now having a KH reading, though I do occasionally use it for higher accuracy in pH tests)
Tapwater parameters with the same test after conditioning:
0 ppm nitrate, nitrite, ammonia, chlorine
300+ ppm GH
It's hard to read the KH reading but I'd say it's probably around 180 ppm. The scale is really bad, though (120 then 180 then 300, and the colors are all a dark bluish green to boot), so it could be anywhere from 120 to 300 (I unfortunately can't seem to find a better KH kit at my local pet store).
pH ~8.0
Pretty much standard heating/activated carbon filtration (not my first tank so I wouldn't worry about this too much); there isn't any underground filtration however. There's also a simple air pump, though it's small relative to the tank.
I don't think the tank is all that heavily stocked; there are 8 fish, the largest by a solid margin is a gold severum that is about 3 or 4 years old (the tank is about 4 years old), he's probably 8-10 inches or so, the others are half his size or less, mostly much smaller than that. The most recent death was a kissing gourami last week, whose eye popped out overnight; he died by the end of that evening. He was probably about 2 years old, and I think it was probably some kind of physical trauma, especially since he had had some physical trauma before. All the fish are at most semiaggressive, and there are no real plants.

That said, my actual question is in regard to the fact that my carbonate level seems much lower than I have read that it should be. I have read it should be around 120 ppm or so (equivalent to about 9 or 10 dKH). My pH is also a TINY bit low (especially if the tank goes a few weeks without a water change, such as this past month when we ran out of water conditioner for a while, when it starts to drift down more towards 6.2-6.4) but not enough that I would worry too much about it, though I could be wrong about this. I do pretty frequent water changes; for a while when we were having issues with cloud eye I was doing very frequent water changes (sometimes as much as 15% a day for a few days in a row), which improved things somewhat. More recently I've mostly done 15-20% every one to two weeks.

So as the title implies: is this a problem, and if so, how should I fix it?

Sorry if this is an extreme repeat question or a really dumb question, and thanks in advance.

Latro 10-26-2009 08:05 PM

Oh, I should mention, I realize the pH of the tapwater is quite a bit higher than it needs to be; if bumping up the KH is necessary and this causes the pH of the aquarium to rise up toward the level of the tapwater (which one would predict), I may perhaps want tips on things other than phosphate buffers (why do they sell those accursed things, especially without clearly stating what they are on the bottle?) to reduce the tap water's pH towards the general vicinity of 7 (probably closer to 6.8).

yhbae 10-30-2009 12:38 PM

IMO, you are getting too concerned with your water parameters. Most species can live in wider variety of water parameters as long as they are introduced slowly. There are exceptions of course (e.g. African rift lake species)

Try measuring your tap water parameters after keeping it in your room overnight. pH is not accurate when it is straight out of tap.

What kind of species are you thinking of getting?

Byron 10-31-2009 11:04 AM

You have some interesting numbers between the tap water and tank water. A GH around 300 indicates fairly hard water. Usually the two hardness measures are close, so the KH (carbonate hardness which is the calcium and such) will match the GH which measures calcium and magnesium plus a few other minerals. The higher the KH, the more resistant to pH shifts your water will be; the lower, the less resistant. This is crucial if you neglect weekly partial water changes, as you indicate has been the case. A KH of 30 ppm is indicative of low carbonates so there is little buffering capability oin the water.

The nitrification cycle allows the water to gradually acidify over time; increasing the hardness will counter this natural occurrence. The buffering capacity of water, the KH, works to maintain the same pH as mentioned above. however, this can be a risky business, and if actually needed should be done by a safe means, such as using a calcareous material like dolomite, cruswhed coral, or marble chips that will slowly dissolve and add calcium to the water, raising the hardness. But the needs or preferences of the fish should be the governing factor in taking any such action to adjust water parameters, not what someone says is the "ideal" ranghe. Fish are different, and will always be healthier in suitable water parameters. But a fluctuating condition is even worse than a steady one that may be slightly outside the "preferred" range.

The pH change is also linked the the nitrates, and a reading of 80ppm is high. Most aquarists suggest keeping nitrates below 40ppm, and around 20ppm or less is the ideal range. Regular weekly partial water changes of 40-50% is the best way to achieve this.

I would also get a good liquid test kit, such as the API, for hardness (they have one that measures both GH and KH), pH and nitrates. In an established tank I wouldn't bother over ammonia and nitrite because the pH and nitrate will be indicators of stability, but then I have all planted aquaria which makes a big difference. And if your pH remains below 7, ammonia largely changes to ammonium in acidic water and ammonium is not toxic to fish.

I would have more thorough tests done on the tap water and tank water for hardness, either with the API test kit or through your local fish store. If the latter, make sure you get the exact numbers, not some general "it's fine" or something which means nothing really. In the meantime, I would do nothing to alter water chemistry as it would be comparable to groping in the dark. When you have the new numbers, get back to us.

However, I would certainly commence regular weekly partial water changes of 40-50% and stick to it. Aside from the above issues, this is the single most important aspect of maintaining healthy fish especially in a non-planted tank with large fish. The build up of toxins in the water that can only be removed by changing the water is very detrimental to fish health long-term. No filter can completely remove toxic substances like urine and liquified solid waste. And these increase at an astounding rate.


Latro 11-04-2009 08:26 AM

So essentially my general stance thus far (consistency about water changes) is the way to go but I should be doing even more of it, then?

Also, you say 40%-50% weekly, I imagine it's not the best idea to do that all at once, right? 20-25% twice weekly seems more fitting?

Also, when I used my liquid API test kit (which doesn't have hardness readings) it indicates about 40 ppm nitrate, if I remember correctly. I had just gotten accustomed to using those woefully inaccurate strips for general use since I was largely monitoring KH.

Byron 11-04-2009 01:23 PM


Originally Posted by Latro (Post 268608)
So essentially my general stance thus far (consistency about water changes) is the way to go but I should be doing even more of it, then?

Also, you say 40%-50% weekly, I imagine it's not the best idea to do that all at once, right? 20-25% twice weekly seems more fitting?

Also, when I used my liquid API test kit (which doesn't have hardness readings) it indicates about 40 ppm nitrate, if I remember correctly. I had just gotten accustomed to using those woefully inaccurate strips for general use since I was largely monitoring KH.

Aquarists used to (and some still do) advocate changing less water more often, and I was one of them--until recently. There is an excellent article on this topic in the November 2009 issue of TFH that clearly proves that larger water changes once a week are much more beneficial. Studies cited therein show that toxins in the water are more diluted with a major pwc once a week that they are with daily smaller changes. Major changes every day would be ideal, but most of us don't have that kind of enthusiasm. Once a week, 40-50%, works. Interestingly, I have been doing this for 15 years without knowing how beneficial it really was; the fish just seemed to like it, and I've never had problems with water chemistry, so I did it. Now I know why it is so successful. So, do the weekly pwc and change 40-50% and your fish will be healthier. If you can manage two such changes a week, even better.

Nitrate at 40ppm is not bad, that is the upper level that most aquarists recognize, while preferring to keep nitrate below 20ppm. However, your API test kit has an issue. The instructions for Regent #2 say to shake the bottle for 30 seconds, and failure to do this could cause inaccurate test results. I learned elsewhere that this Regent #2 should be shaken for 2+ minutes. Aquarists were getting high nitrate readings, and after testing with the Regent #2 shaken for 2-3 minutes had much lower nitrate readings. Obviously the regent needs to be shaken for 2+ minutes to obtain more accurate results. Try this and see if you still get 40ppm or a lower figure. As well, a weekly pwc of 40-50% will keep nitrates below 20ppm, unless there is something affecting this such as biological problems in the tank, nitrates in the tap water (some areas have this), etc. Try it and let us know.


Angel079 11-04-2009 08:10 PM

I'd like to add that the strips do help you to see what range you're in. Let's say you test with a strips (quick & easy) and have a nitrate of 180ppm with the strip, it'll tell ya then & there you got a serious issue. Even if you were to re-test this then with the kit and "only" have a nitrate of 150ppm you'd STILL have a big issue.
I prefer test kit too, BUT to give you a general & quick idea what's going on strips work and if the "right" parameters read 0 on it, i'd not see the necessity to retest with the kit. However if you do have a 'odd' reading and need to figure out what the issue is retest with the kit and get accurate results.

And I can only underline what Bryon said, in all my tanks over the years I always did about 40% water exchange each Sat and my tanks, plants & fish loved me for this for many many yrs.

PS Latro, donno where you are, but I can not find the KH for the API test kit here neither in TN, maybe we'll need to get Bryon to mail us some :-)

Latro 11-05-2009 06:43 PM

This is probably overkill, but on this issue of nitrate test accuracy:
It's very difficult to quantify something like nitrate, which is not very reactive, especially in a complex ionic mixture like aquarium water. Even the liquid methods really aren't going to be all that great. Really, if you actually wanted to REALLY know the answer, the easiest way to do it would probably be to take a sample and put it into a GC-MS. Assuming you could rule out the presence of ammonia and nitrite using other methods (which is much easier, since they are much more reactive), then your relative abundance of nitrogen atoms would be your relative abundance of nitrate ions. A little math gets you to a number in ppm after that.

Carbonate is the same way: it's extremely easy to quantify if it's the only pH-influencing substance other than water in the mixture (you'd just do a pH titration, basically). Once it isn't (and it certainly isn't in an aquarium), though, things are much more difficult.

Anyway, thanks guys. In a little while I'm gonna go ahead and do a bigger water change; in a couple weeks or so (after 2 or 3 big changes) I'll get back to you guys and see if the parameters are any better.

Latro 11-21-2009 01:35 PM

Before this most recent test I ran out of strips, which is a bit unfortunate, as I can't actually measure KH now. However, after having done 2 ~35% water changes (the container I have holds about half this much) in a span of two weeks, my pH is holding steady at about 7 over a span of a week without a change. It might have fallen by at most 0.1 (I've been testing pH daily, the color has changed enough to be seen but not enough to go from one part of the card to another). This is quite a bit better than what I had before, so I imagine my KH has risen pretty considerably. Thanks guys!

Angel079 11-21-2009 03:16 PM

That's good news! Congrats!

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