Cycling new tank, will my soft, acidic water cause problems? - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 4 Old 01-11-2012, 03:33 PM Thread Starter
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Question Cycling new tank, will my soft, acidic water cause problems?

Hi everyone,

About a month ago I set up a 60 litre coldwater tank with a few live plants. I gradually stocked it, it now has 8 White Cloud Minnows and one Rosy Red Minnow (I will try to source him a couple of friends once my tank is stable).

I didn't know about cycling when I set up, but after browsing this site and others I am now monitoring the water quality every day with the API liquid tests. Ammonia did drop to 0 and nitrites rose to .25 for a week or so, but then the ammonia rose to 0.25 and nitrate 0. I cleaned the filter sponge in tank water, I think this must have killed my bacteria :( I am testing the water every day and doing large (around 50%) water changes whenever I get an ammonia or nitrite reading.
I haven't had a positive nitrate reading yet.

So, I think I understand the basics of cycling now, but I am still very confused about pH, kH and gH. My test strip says pH less than or equal to 6.4 (the reading doesn't go any lower :s). I've ordered the liquid API pH test to get a more accurate reading; it hasn't arrived yet. Test strips say kH - 50, gH -50. Should I add some shells or something to increase the kH to increase the buffering capacity? I've been reading about hardness and pH but I got very confused! So I haven't attempted to change anything until I got some advice from some more experienced fish keepers :) That's where you guys some in!

Now I've just read that ammonia is less toxic in acidic water, is this true? I feel really guilty every time I get a positive ammonia reading because I worry I'm damaging my fish for life! Will it be less toxic in my water?
I stood some tap water overnight and tested it, and got ammonia - 0, nitrite - 0, nitrate - 0 and pH less than or equal to 6.4.

Detailed information about my tap water is available here:
If someone could have a glance through and advise me I would be very grateful! In particular, it says that the average alkalinity (as HCO3) of water leaving the treatment plant is 23.7 and the average hardness, (total as Ca/l) is 34. I've read about pH buffering but got very confused... Will my pH be likely to fluctuate, and if so should I add some shells or something to raise the kH?

Oh, and I forgot to mention that I use the API water conditioner when I do water changes to dechlorinate and remove metals... It doesn't remove ammonia, nitrate or nitrate from the water, though. I've read about "Prime", some people recommend it and others say it's best to avoid such chemicals. Any opinions?

I'm using a 600l/h "All Pond Solutions" internal sponge filter. No heater. Temp around 18 degress C. Lighting: one 15w Fluval bulb.

I also have a 110 litre tropical tank with 6 Cherry Barbs and one Kribensis, will my soft, acidic water cause problems for these guys?

I am very confused, who'd have thought that keeping some fish would be so complicated (and so expensive!). But before I start messing around trying to change the pH or kH anything I thought I'd seek the advice of experienced fishkeepers as I really do not know what I'm doing! So any advice would be very much appreciated :)


Last edited by Rayemond; 01-11-2012 at 03:45 PM.
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post #2 of 4 Old 01-11-2012, 04:29 PM
prime is fine to detoxify chlorine etc. but not fine to just add when ever you have a spike you can do it and it is probably better then loosing fish but not recommended on the long run
and for the cycle.. sadly if each time you see a reading you do a water change it will take for ever to have the cycle done :( and as for ammonia in water less then 7.0 is not toxic , but in water bellow 6.0 it is very hard to get a cycle done because bacteria enter a state of sleep and do almost nothing. as for raising ph I would wait untill Byron or someone with alot of experience gets intoo the subject :)
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post #3 of 4 Old 01-11-2012, 04:40 PM Thread Starter
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I've read so much about ammonia and nitrite being so toxic and painful for the fish that I feel really guilty when I get any reading above 0 and do a massive water change! I read that the bacteria live in the filter and substrate and aren't really present in the water, so I thought large water changes wouldn't slow the cycling process by much? I have been hoovering the gravel every water change too though, should I stop doing that to give the bacteria a chance to grow in the gravel?

I didn't know about the bacteria becoming dormant when the pH is below 6... I wonder if that could have caused my nitrite to drop to nothing and my ammonia to jump back up? I didn't think that cleaning the filter sponge in tank water should kill them all off... I don't actually know if my pH has dropped below 6 though, I will post my results from the liquid test when it arrives.
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post #4 of 4 Old 01-11-2012, 06:01 PM
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First thing, welcome to Tropical Fish Keeping forum.

In my experience, with live plants (esp faster growing ones) you should not see ammonia or nitrite. Have you tested your source water (tap) for these? Just to be certain; the numbers in the water report are minimal but one never knows. Provided the pH remains below 7, ammonia will change to ammonium which is basically harmless; plants (and bacteria) use ammonium/ammonia, and ammonia tests will show ammonium or ammonia as straight ammonia. I would not worry over ammonia/ammonium in acidic water, and stay with regular weekly water changes of 30%. I wouldn't change more than this due to the significant difference in pH. Test the tank water pH immediately before the water change, and then test it a couple hours after and again the next day. This will tell you how much it is fluctuating; post the numbers.

To the pH. It is very high in the water report, 8.11 the average. This can be caused by various things beyond calcium and magnesium hardness, which is low at 35 average. With the GH this low, and the KH (alkalinity) at 24, the pH will tend to lower in an aquarium as the increase in carbonic acid affects the water. With soft water fish, this is not likely to cause trouble, though there is merit in buffering it a bit to prevent it going too acidic. The best way to do this is with calcareous gravel/sand, but it takes very little. At this point, you might want to have a read of this article for background:
Don't hesitate to ask questions.

The API pH test kit goes down to 6. My tanks lower to 5 and I suspect below. I have a Tetra kit that goes down to 5 so i know some of them are there. I just let them drop, since I have wild caught fish from South America and this is fine. The lack of GH (calcium) is causing some issues with the plants more than the fish. My tap water GH and KH are down to near-zero.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If youre going to take it under your wing then youre responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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