acid problem in freshwater aquaria

Question
1) Is there really such a thing, as we've been told, as "old tank syndrome" i.e., tanks that have been in use for several years tend to get acidic easily? (Two 55-gallon acrylic tanks, new in '95, used for 3 years, dry for 3, in continuous use since 2001.)

2) Is the 1" of fish per gallon of water rule-of-thumb a good one? (We're overpopulated 'cause the baby jewels survived and thrived.)

3) Could "driftwood" in the tank be contributing to the problem? (One tank (~50% water change)went from 6.6 to 6.0 in three days; the other (~2/3 water change) went from 7.0 to 6.1 in the same period.)  

Answer
Hi Archie,
 I have never heard of the "old tank syndrome" per se.  If a tank has plants or wood in it, over time they will decay and that will make the tank more acidic. The solution is to do regular weekly partial water changes.  

 The 1" rule is only the roughest of guidelines, intended for people with no experience.  The actual number of fish you can keep in a tank depends on many, many things.   You can keep dozens of baby fish in a 10 gallon tank, but you certainly can't keep one 10" cichlid in a 10 gallon tank.  The most important thing is how often you do water changes.

 In general, I recommend 25% water changes.  50% or larger water changes can be pretty severe.  

-- Ron
  rcoleman@cichlidresearch.com
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