Hi,

I have a new heavily planted 136 Liter tank which has been fully fishless cycled and can now convert 5PPM Ammonia to 0ppm Ammonia & 0pmm Nitrite. The process had taken 31 days, I completed 2x 75% water changes and tested with the following parameters:-

Ammonia (NH3/4)...................0.0
Nitrite (NO2)...........................0.0
Nitrate (NO3)..........................50
Potential Hydrogen (PH)..........7.0

So, I then visited 4 LFS in my area and purchased 6x Rummy Nose Tetra's from 1 LFS & 6x Cardinal Tetra's from another LFS as they appeared to be in better health at the 2 different stores. They were very helpful at both the stores and after showing them my water parameters above said it shouldn't be a problem to keep these fish, although the Cardinal Tetras are more sensitive than most other fish.

I have today (3 days later) tested the water again, using the full Nutrafin Master Test Kit as follows:-

Ammonia (NH3/4)...................0.0ppm
Nitrite (NO2)...........................0.0ppm
Nitrate (NO3)..........................10ppm
Potential Hydrogen (PH)...........8.0
Carbonate Hardness (KH)........70ppm (3.92 dH°)
General Hardness (gH)..............200ppm (11.2 dH°)
Phosphate (PO4)......................1ppm
Calcium Concentration..............60
Calcium Hardness.....................150
Magnesium Concentration.........12
Magnesium Hardness................50
Non-Chelated Iron....................0
Chelated Iron............................0

My concern is that although my tap water has a PH of 7.4, in my tank it has raised to 8.0, why? This has then made me worry specifically about my Cardinal Tetra's as I know they like softer and lower PH parameters. All my fish seem fine though and are swimming around like crazy, they all seem to be eating well too so do I really need to worry?

I have however heard that using pH adjusters can lead to trouble, as you may find that you have to keep "tweaking" the water to keep it relatively stable. If possible, tap water is the best bet (even if your pH is not what's recommended for a certain fish), except maybe if you're specifically trying to breed certain fish. Keeping PH stable is more important and most fish will adapt to a PH range out of their normal environment. Is this also true for Cardinal Tetra's? If it is, how can I keep my PH Stable?

Finally, with my water parameters as they are, is there anything else I should worry about and if so, how can I fix it? I know about the iron and I am planning on getting some fertilizers to fix this, any suggestions? Also, I think my Phosphate is too high, gH is too high and my KH is too low, any thoughts please?

The only other things I think are worth mentioning is that I have 1 rock (which I tested with vinegar first, it's ok), 1 large piece of bogwood, my substrate is 100% eco-complete and I have an Eheim Professional II External Filter.

Thanks,

Richard.

The cardinals will be fine, your KH and GH are not high, I have kept them in less ideal conditions. On the ph; to know the actual ph of your tap water you need to leave it out for 24 hours to remove the Co2, running an airstone will get the Co2 out more quickly, my ph can go up almost a whole point after 24 hours, its not a worry having the different ph when doing water changes, it gasses out pretty quickly you often see the bubbles after the water change. Your KH is fine anything over three is more than enough to keep the ph stable once regular water changes are done. 1 ppm phosphate is low, don’t see how that could be a problem, if you have plants you might even want more than that. I have never tested for Iron its hard to get accurate results but don’t think there is anything to be concerned about. It looks to me that all is fine with your water for keeping cardianls.