Water Quality Tips - Possible Emergency?

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Nov 22, 2006
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Further to this thread I have spent a while water testing today! Thank's to a couple of water changes the ph has now improved to just over 6 so that problem is dealt with, I have encountered a couple of other things though and despite a lot of reading I am still a bit confused about them!

Firstly through some web research I worked out ideal water chemistry for the fish I keep (with very general values) (see other thread for fish list):

Optimum pH: 6.5
Optimum GH: 4.0-10.0
Optimum kh: 2.0-4.0

Then I tested my tap water:

Current Tap Water PH: 7.0
Current Tap Water GH: 12.0
Current Tap Water KH: 7.0

Then I tested my Aquarium Water:

Current Tank PH: 6.2
Current Tank GH: !42!
Current Tank KH: 1.5

So although my pH seems to be going in the right direction I now know the tank water is extremely hard (most guides say 22+ GH is 'very hard' and mine is 42). However the tap water we are using for water changes only has 12GH.

My KH on the other hand is very low in the tank (1.5) compared with the tap water (7.0) as 'andyt_uk' suspected in the other thread.


1) How serious is the high GH level in the tank, the fish are all behaving normally and look healthy, so it's possible it has been like this for a long time and they are used to it - I am presuming it should be lowered anyway especially as I plan to add new fish.

2) What is likely to be causing the water to increase so dramatically in hardness in the tank when it comes out of the tap at 12GH - is there likely to be some kind of contaminant in the tank?

3) What can I do about it? Should I just continue with frequent water changes and monitor it closely or is there something more pro-active I can do.

4) andyt_uk kindly recommended in the other thread to: "add about a 1/4 teaspoon of bicarbonate of soda into fresh water when you do a water change - you should see KH increase, pH will get closer to your tap pH, and the increased KH will help stabilize the pH". I haven't done this yet but plan too - is this still advisable in light of the the very high GH level. On my KH testing kit instructions it recommends using PROPER pH to set pH and increase KH level, when my water naturally reaches 6.5 could I use the 6.5 version to boost the KH and maintain the pH?

p.s. I performed every test twice to make sure.
What decor, substrate is in the tank? It looks as though you may have some lava rock (dark red/brown, rough, with lots of small crevices) and slate. These increase GH, but then they should increase KH as well. Only thing I can think of to reduce the KH would be excess nitrates. You say nitrate is fine in first thread--what's the measurement? I've been told test kits do indeed expire; certainly if it's years old, it remains a question. In lieu of buying a new kit, you might take a sample to LFS, and see what results they come up with.

Beyond that, you might put one of the rocks in a bucket of tap w/ an airstone running. I don't know how long it would take to show results, if indeed that's the culprit, but may be worth a try?

GH, KH can be measured in degrees or ppm...can you confirm your results are in degrees?
thanks for the reply reg2k2

will get a new nitrate kit tomorrow and test again

my GH kit is definatly measuring in degrees (it's dropped to 39 today after a 20% water change)

I've taken the two small reddy rocks out (think they are actually some kind of granite) as they are mainly taken over by algae now anyway so will see if that helps at all.
ok i went a bit test kit crazy and can now report the following:

Current Tank PH: 6.4
Current Tank GH: 39
Current Tank KH: 1.0
Current Tank Ammonia: 0.25ppm
Current Tank Nitrates: 80ppm
Current Tank Nitrites: low/none
Nitrate reading of 80 is high (>40 recommended). So this may be bringing down the KH, and in turn the pH. What is nitrate from tap, if any? Filtration seems adequate, and you don't seem overstocked, lightly stocked actually. Could be due to lack of cleaning.

I would suggest daily 25% w/c's w/ gravel vac. Test.

Ammonia s/b at zero. Have you replaced filter media perhaps?

I would hold off on adjusting the KH/pH for the moment, and see if they don't come up through the water changes, as the readings from tap are fine.

Regarding rocks. I'd like to recant the above and say that slate s/b inert, and I'm finding mixed thoughts on lava rock. Granite should also be inert. However, you could try the 'vinegar test' on the rocks you have. A few drops, if it foams/sizzles, it's likely to affect the water. Might try it on a pinch of gravel as well.

AFAIK, GH is really only a concern if you intend to breed. However, I would be concerned as well w/ it being so very high (but prob. not an emergency). From what I can find, it can affect cell/internal organ function. On the other hand, for the fish you have, according to Baensch: x-ray tetra: to 35dGH, flame tetra: to 25dGH, cories: to 25dGH, khuli loach: 'soft', clown loach: to 5dGH. And, according to PlanetCatfish, most plecos are pretty adaptable.
So, loaches aside, it may not be as dire as it sounds, although it's obviously something about the tank that's bringing it up so high.

I would say the main concern right now is seeing that your pH is stabilized.

I was just taking a look at your tank pic again, and noticed a big red tail in the back....those are not khuli loaches, but rather clown loaches. They grow large, may need bigger tank..research this. At current size, I still think you're prob. stocked on the lighter end. Or is that an albino khuli I see at the top of your fish pic as well?
strange GH readings there mate
has your tank been allowed to lose water due to evaporation?
that would increase the GH, as would the introduction of minerals by having slowly dissolving rocks in there, which with the low pH you had the action of the acid on certain rocks could cause them to leach more hard minerals than is usual - once your pH is stable you may be able to reintroduce those rocks if you wanted.
again water changes is probably the safest way of getting things back to normal.

oh yeah, add the dechlor ALWAYS :)
a tiny amount of bicarb with the water changes will increase the KH, help raise & stabilise the pH.
water changes will reduce the nitrAtes (so they say, mine are high too and i just cant seem to lower them)

also point out i dont like to see ANY ammonia at all - how did that get in there? could we be seeing a mini cycle? a low pH may also cause that - killing (or retarding) the good bacteria...

oh and your KH testing kit probably recommends using PROPER pH because they make it :) just my opinion - time will tll, you may need something like that, but i'd wager everything will settle out quite nicely with the water changes and advice already given :)

good luck
thanks for all the advice reg and andy

I'll continue with the water changes as so far they're definately changing it for the better :)

Updated figures:

ph 7.1
gh 13
kh 7
nitrate 5.0ppm
Ammonia 0ppm
Nitrite 0

ph 6.6
gh 37
kh 1.5
nitrate 80ppm
Ammonia 0ppm
Nitrite 0.1

reg: I did mention in my first post about the clown loach (he's being rehomed as soon as I get the water better as you're right he does need a bigger tank and some friends)
strange GH readings there mate
has your tank been allowed to lose water due to evaporation?
that would increase the GH, as would the introduction of minerals by having slowly dissolving rocks in there,

I was thinking the same. Topping off the tank to replace evaporated water will increase the amount of minerals in the tank since minerals don't evaporate.
I did mention in my first post
oops, you certainly did. :blush:

Glad to see those nitrates aren't coming from the tap.

Keep us posted.

ph 6.9 (up)
gh 30 (down)
kh 4.0 (up)
nitrate 80ppm?

Nitrate is a bit weird because neither me or anyone who has been around can actually tell which colour on the chart it's closest to (could be 40 80 or 160!). It should be more obvious when it drops below 40 though which it hopefully will soon.
everything still fine except for nitrates they are coming down slowly though, rehomed the clown loach and have 6 new corys now all healthy.

thanks again for help

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