Hi There,
I'm new to tropical fishkeeping and am currently "fishless cycling" my first tank. All seems to be going as expected. The Ammonia has dropped slightly and a small amount of NitrIte is now present (after 6 days ). I have a few questions tho if anyone can answer i'd be gratefull.
1/ I've read about the `innevitable` PH crash !! i've got my head round the Nitrogen cycle but can someone explain why this is and ways to remedy it prior to stocking?
2/ I've started looking for suitable fish for a newcomer and Danio's seem to be mentioned as quite hardy fish and good for new keepers/tanks? sound about right ?
3/ Some fish i've seen in stockists say happiest in (shoals of 6 or more) for species such as tetras etc. does that mean
just that species ie all neon blue tetras or could i perhaps get 3+3 ( all neons but differnet colours ) ?
Thanks for any replies forthcoming
simb07
Hi simb07,
1) First of all, the notion of a pH "crash" is a term we've tried to limit to the period of fishless cycling, not after you have fish. And it is not "inevitable" since your susceptibility to it is based on how much "buffering" capability your water has. The "carbonate hardness" property of water is a good representation of the buffering capability that the water has. If this is too low, the ability of pH to remain stable against the increasing acidity caused by the cycling process will fail. Carbonate hardness will have dropped and the pH will go down. When the pH gets to 6.2 or below, the *growth* of the bacteria will stop. The bacteria will not die, it will just stop growing. So when people say "pH crash" they just mean the pH measurement has gone down to 6.2 or below.
In the hobby, we are able to buy test kits to measure "KH" (Carbonate Hardness (K because of original german)) (strictly speaking, the kits actually measure something called total alkalinity as a surrogate for carbonate hardness, but it works. There are chemists that feel the term KH should be dropped from the hobby and "alkalinity" used instead.) We use the german degree scale to communicate the results. The simple rule of thumb is that if your KH is 4 or below then your pH could make quick changes and should be watched. If its 5 or above, you have more time on your hands.
Historically and technically, carbonate hardness is kind of interesting. You may have heard it referred to as "temporary hardness" which, together with "permanent hardness" make up the overall mineral content of water. Actually its best to step back and say that Total Dissolved Solids (TDS) is the sum of all the inorganic substances (of which mineral content or "hardness" is the main component) and organic substances in the water. There is also a term "General Hardness" which I feel is often used for the same meaning as "permanent hardness" but came about because of the measurement scale "dGH" "degress of general hardness".. a scale used for both temporary and permanent hardness measurements. (got all that?
)
If you want to ignore all that pseudo-science and just be practical, just watch your pH and if you have trouble with it dropping a lot during fishless cyclng you may need to invest in one of the liquid alkalinity tests (called a KH test, lol) so that you can watch if its 4 or below and know ahead of time when pH is going to drop on you. Or... just ask!
2) Danios (zebras and all the newer variations) are indeed wonderful, active little hardy fish usually considered excellent at being in the first set of tank introductions. But they do need space to swim fast, so tank shape and volume come into it. Among the TFF members there are any number of opinions about minimum tank volume and horizontal minimum swim space. They are not shoaling fish (at least I don't think so technically) like tetras but they do greatly enjoy and stick with their kind.
3) "It depends" lol, the shoaling fish will indeed know which types are really "theirs" but mixing of different "color variants" etc. has often been observed and will happen. Trying to adhere to minimum shoaling numbers is an important and wonderful thing and if you observe your fish closely you will see its truth more and more. Different species seem to have different behaviors as you get down at their minimum and different ranges through which you will observe increasingly positive things as you raise the numbers, up to some point upward of which they will just seem to stay well-adjusted all the time.
Hope that helps,
~~waterdrop~~
