capper

We have 6g, 16g, and 46g tanks. Our 6g tank houses 4 platies. They always have seemed quite happy and active. Last week we changed the substrate from a basic stone type to a soil substrate. Over the past couple of days I noticed them extremely quiet and hiding in a rear corner of the tank. Today I did a water test and noticed that the PH was about 6.5. It had been 7.6 or 7.7 previously. The substrate had a major impact on the PH level and likely has caused problems for our platies. I did a 1/3 to 1/2 water change and got the PH back up to 7.0. Our tapwater here (in Tokyo) is about 7.6 or 7.7. Any suggestions as to how we should proceed? I was hoping to move them into one of our other (larger) tanks so that I could have a small number of guppies in the 6g. However, guppies preferred PH is about the same as platies. Is there anything I should do to raise the PH if we plan to keep these type of fish in the tank?

Second problem... Our 46g tank is a community tank with several tetras, platies, African Lampeyes, a pleco, a few cories, and lots of shrimp. We have 12 Cardinal Tetras and have had them for quite some time. Suddenly today we noticed one is very sick and near death at the top of the tank. I did a water test and everything seemed normal. The ammonia level was a tad above the 0 level. However, all the fish seem healthy and fine. Any suggestions? I know that Cardinal Tetras prefer a lower PH. However, I was previously advised that they'd be fine in 7.5 or 7.7 water as they could adjust. Besides, we have other fish in there with slightly different needs.

Butterfly

Usually if fish are slowly acclimated they will adjust to just about any ph.
Since besides your filter the next largest amount of beneficial bacteria live in your substrate. When you changed the substrate you threw out a lot of your beneficial bacteria. I think your tank is going through a mini-cycly. Keep a watch on your water tests for ammonia and be prepared to do a water change.
what kind of soil are you using and what are you using to keep it stirred?
As for your 46g sounds like a really pretty tank. Not knowing how many of what you have ... could it be a little over stocked? Cardinals are super sensitive to ANY ammonia.
Also could they be old? Hope that helped- sorry to answer questions with more questions
Carol

capper

I think you're right about changing the substrate. I did a 1/3 to 1/2 water change yesterday to try and get the PH back up for the platies. I am mainly worried about the change in PH level. I am not sure what the soil is called but they are little round balls (not crushed or really fine dirt). It is special (and expensive) freshwater aquarium soil. The ammonia level when checked yesterday was not 0, it was slightly over that. However, all 11 of our other Cardinals are fine as usual. They have probably been are most durable and natural-acting fish. The sick one died last night.

Yes, our 46 is a beautiful tank! It is FULL of plants and bogwood in addition to platies, glowlights, cardinals, rummy noses, african lampeyes, cories, a pleco, and 3 kinds of shrimp. It's really fascinating to say the least. One concern I do have is that I find the platies -- since they are top-feeders -- tend to eat a much higher percentage of the food than the other fish (tetras / lampeyes). Sure, they're bigger but they tend to hog as well. I know you can drop foods that will not stay at the surface very long, but they also tend to eat more in other parts of the tank as well. Thanks for your reply.

Butterfly

When I have hoggy top water feeders I tend to drop some food on the top and then pinch a bit between my thumb and forefinger, hold it under water and when it gets wet drop it. That way some floats and some slowly drops through the water. But doing this you have to be careful and not feed too much, don't want to pollute your tank if your fish look fat and healthy they are evidently getting enough
I am not familiar with that type of soil, it would be interesting to see what it looks like.
Carol