Ph in freshwater fish with Molly/Livebearers

Question
I have many Molly's in my 20 gal tank.  Just did 25% water change and tested the water to find the pH is at 6.2, nitrates high as well.  I added Stress Zyme, a teaspoon aquarium salt, and 1/2 tsp (all that was left) of Ph netralizer.  The pH didn't adjust.  I'm concerned as there is one mother who looks like she is going to burst with babies, but I feel that the pH being so low will prevent her from giving birth and likely cause her demise.  Am I off in my thinking.  It's too late to go to the fishstore. Tomorrow is a work day...is there anything I should do immediately.  Otherwise, I'll do what I can tomorrow evening to adjust my tank.  My main problem is too many fish (Molly itis) and only doing water changes 2 x month.  Also likely overfeeding because there are so many hungry fishes (or appear hungry).

Thanks for your help.

Lynn

Answer
Hi Lynn;

It is best not to alter the pH with chemicals. Using chemicals can be dangerous and cause fluctuations that are very harmful, actually more harmful than your fish living in a pH of 6.2. It really isn't that bad a pH anyway. The fish are fine because it's what they are accustomed to. They need a stable pH, not a certain reading. You just don't want it to go below 6.0. You can raise it slowly and naturally by making partial water changes more often. The gravel needs vacuuming too. There is likely too much waste in there from the overcrowding and it has "used up" the buffers that help the pH stay higher. The excess waste is also the reason nitrate is elevated. I know it will be difficult, but if every day for a week you could change 10% to 25% and vacuum a portion of the gravel at the same time you will see an improvement. Cut back on food too and replace a few feedings with one of these 3 or 4 times a week; part of a leaf of romaine lettuce, cooked green beans, cooked peeled peas, cucumber slices or cooked shredded carrots. Veggies don't rot the same way regular foods do so they contribute less to your nitrate level and your mollies will do what they like best; nibble. Mollies really need the fiber that veggies provide.

Fish will beg for food because it gets them some. It's as simple as that. They have learned that food is available every time they perform a certain behavior. They really aren't hungry. Just a habit they have learned. In their natural environment in the wild, fish perform certain hunting and foraging behaviors and it yields food too. It just isn't as abundant and easy to get like from a huge hand dropping it in. They have to really work for their supper and they use calories in the process and their wastes are biologically processed in very large bodies of water by plants, algae, sunlight, etc. Perfectly healthy and natural. Our little eco-systems that are our aquariums are lacking many of those natural elements as we dump food in and our little finned friends wiggle with joy every time they see us and have much less room to burn off those calories and nowhere for the waste to go but down in the gravel. ;-)

Followups welcome...

At Your Service;
Chris Robbins