Zander_The_RBP;3778573; said:
So you'd recommend a 75 percent water change to someone (since JP said you shouldn't do any higher then 50 percent)?
How can you possibly match up the temperature of a tank when swapping out such a large portion?
good sign??
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So you'd recommend a 75 percent water change to someone (since JP said you shouldn't do any higher then 50 percent)?
How can you possibly match up the temperature of a tank when swapping out such a large portion?
Zander_The_RBP;3778573; said:
there's more to water chemistry than just pH and water temperature. depends on your tank size it might not be possible to match the water temperature.
also the pH level of water in an established fish tank will be different than water coming straight out of tap, most like not by much but will be different especially if there are driftwood and plants and other organic decors in the tank. sometimes substrates can also alter pH level.
the mineral in water will effect water chemistry, sometimes with sudden increase of certain mineral may cause algae bloom.
can you change more than 50% of water? certainly but most likely there's no need for such large water change. the amount of water change really should base on what is needed to bring down the nitrates. Unless your seeing ammonia, nitrites or high nitrates I wouldn't do too big of a water change.
also, excessive of water change can put the tank into a mini cycle.
any more than what's necessary it's just a waste of water.
a water change will NEVER trigger a mini cycle bacteria live on objects in the tank not the water coloumn theres enough threads on this forum about this subject and the genernal consensus on this forum is 50% or more water changes are perfectly fine and better than smaller onesjp80911;3779054; said:
the pH in an established tank IS the same as comming out of the tap if its not your not doing enough water changes or your water isnt buffered well enough or you have driftwood or co2 which is why i said assumming you haven't tampered with pH yes it does drop without any tampering over time but not a significant enough degree that the fish will get "shocked" everytime you do a water change (assuming on a weekly basis)
discus keepers routinly do 90 -100% water changes and they have the most sensitive freshwater fish out there but they get there temps perfect
Zander_The_RBP;3779365; said:
yes I do know that the BB are not free flow in water but build on surface such as substrates, filter media, glass, decors, etc.
if the tank has no substrate (all the beneficial bacterias are in the filter media) and water conditioner is used to remove chlorine then you shouldn't have a mini cycle (assuming filter media is not replaced or being cleaned incorrectly). other wise there's can a chance of mini cycle, not saying it'll happen for sure but I won't surprised if it does happen.
also some city water may contain ammonia, if that is the case such large water change can trigger a mini cycle.
since we do not know what kind of setup he has in the tank (such as driftwood or other deco that could effect pH level) we do not know how different the pH level in the tank and in tap water. and I'm not too concerned about pH level unless the tap water pH level is really out of sync, that's why I didn't specifically mentioned it's pH in my original post. there are other water parameters (such as GH)can be effected if the water change volume is too great which can have effect on fish.
as for temperature, depends on tank size, getting the water temperature may not be always possible. getting it right for a 50g tank is very different as compare it to a 500g tank when you are talking about the same % water change.
can you change more than 50% of the water? of course, but there's not need, at least for piranhas unless there's something seriously wrong with the water in tank. or really required by certain species of fish.
I know many discus keepers change large amount of water during water change (some do it daily) but I'm sure they match every parameters before dumping all those new water in their prized discus tank. but there's really no need for that kind of water change when it comes to piranha (which is what OP has and we are discussing). if not done correctly it'll do more harm than good, that's why I generally not recommend doing more than 50%, typically 20-30% weekly will be enough given the filtration system is sufficient enough.
It is my understanding that Light or Darkness alone can change the PH value, not to mention the amounts of organic waste in the substrate. Tannins or Tannic acid that is contained in all plants and trees can swing the ph value if the ph value is already low. Crushed corals can raise the PH value however overtime both acids disipate. Time and temperature also play a role in the PH value- It's pretty obvious to me that fishtank PH is probably always in a state of flux however the changes in the values aren't nearly as dramatic to cause major alarm for most freshwater fish with weekly W/C. Trying to actually control a constant PH thru buffers seems to cause the dramatic harmful swing in PH if your not super constant w/ temp,time,w/c,waste,and buffer however in a Saltwater enviorment this is achieved daily by millions. I do also agree with JP on 50% water changes. If your tank requires more than your probably overstocked, overfeed, underfiltered, and open to all kinds of problems including parasitic activity. However I do not believe that 75% will crash bacterial colonies, if anything it will increase the amounts of fresh oxygen to the tank. Alot of ppl add dechlorinator before they fill the tank, they also wait a few to turn on the pump to insure that large amounts of chlorine don't make it too the pumps biological filter. Cold water from say a gardenhose and large amounts of un-nuetralized chlorine can/will crash the bio-cycle.
Zander_The_RBP;3778573; said:
yeah for all my fish I just feel the general temp with my hand in the tank and then try and match that in the bucket. For both my tanks I do pretty much every other day 50% water changes. My fish stay happy and breed. My water in my 37g never tests over 10-20ppm NO3, 0 NH3, 0 NO2. If there's a pH fluctuation I've never noticed it, and neither has my fish. They all show good color. I'm of the opinion (and there are articles in TFH about it, Time for a Change: A Mathematical Investigation of Water Changes, TFH David E. Boruchowitz. 2009) that the more frequent and large the water change, the more you are simulating their natural environment. Some people who keep discus do 100% daily PWC, and some people have drip systems that continously change the warer.
Also, a lot of fish secrete hormones that inhibit their own growth as well as that of other fish in the tank. The more of that you remove the better. The key to growing fish in my opinion is to provide them with as much clean water as you can afford and have time for.
