Aquarium water Acidic?

Question

Hey all, 

I've had a stable fish tank for a couple of years now. Consistantly, the water has been hard, and has been very alkaline (7.4 range). However, recently, I noted that my fishes fins were looking a bit ragged and bloodshot. I ran the pH recently, it's it's gone totally acidic on me (6.0). So far, I've added some buffer, and did a 30% water change, hoping that the hardness of my tap water would help to balance it out, but so far it hasn't moved much more than to the 6.4 range (this is the third or fourth day of trying to fix it). 

As for the tank, it's 30gal, and contains goldfish and some guppies- which I've had about 3 years now. There is a large hood based filter running right now (filter is made for a 40 gal tank), and I don't typically add a lot of chemicals or anything to the water. Within the past few months, my fish did have a problem with some fungal whatnot, which I cleared up with some tablets. And now, I'm having issues with this. Any ideas?

Red_Rose · Accepted Answer

It sounds like the pH has crashed which can happen sometimes.

Have you tested your KH at all lately?  The KH(carbonate hardness) is a buffer for the pH.  The lower it is, the more easily you can change the pH but the higher it is, the more difficult it will be for the pH to change whether it be from you intentionally altering it or it happening naturally.

If the KH of the water you use to do water changes is 4dH or higher, then this most likely would not have happened.  Also, is the tank a planted tank?  If so, do you add CO2 to the tank?  A more acidic pH is a side effect of adding CO2 to an aquarium.

My suggestion to you is to test your GH and KH(especially the KH).  If it's below 4 then you may want to add something to the tank to keep it at four or higher.

Ianab · Answer

Keep changing the water.

What has happened is that organic waste from the fish has built up over time, enough to overcome the buffering effect of the waters natural hardness. This causes the pH to crash. The problem isn't exactly the low pH, it's the poor water quality thats making the fish sick.

A 30% water change isn't enough to fix the problem as 70% of the crud is still in there. Do a series of 30% water changes until things come right.

30gal is not a big tank for goldfish, thats probably why you are having problems maintaining the water quality. Not sure what your water changes have been up until now, but they need to be more and bigger. Once you get the tank under control it will be fine to do 50% water changes as often as needed, at least every week, possibly more often depending on the size and number of fish.

Ian

? · Answer

If your tap water is naturally hard, and your tank has low pH, something is going on there.  Since you've been fighting this for several days without success, I would probably move the fish into a temporary container, do a 100% water change, cleaning everything except the filter media thoroughly with tap water and a little bleach. Rinse thoroughly. Rinse the filter only in old tank water and keep it submerged in that tank water as you make the water change.  That will preserve your beneficial bacteria.

Return the fish to the main tank after doing proper acclimation but use a net so you minimize the amount old water going into the clean tank.  Sometimes it's better to just start over.

Shirley · Answer

You must keep  up with changing the water as far as I know...because my sister did that..but she decided she didn't want the tank anymore...so we have our pool that totally turned into a pond...we have koi,goldfish and turtles living in there....we lost our pool many years ago because of that...i just go to a pet supervisor...let them know what your doing and they can help you out...don't miss out any details either....

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Aquarium water Acidic?

4 Answers