Decision Making

I have decided to either do the experiment on the effect of temperature on the acidity of juice, or the effect of different types of soils on the growth of plants.
So far, I have found this much information:
1. For the experiment on acidity of juice:
- the independent variable is the temperature of the storage area
- the dependent variable is the acidity of the juice
2. For the experiment the growth rate of plants through different soils
- the independent variable is the type of soil used
- the dependent variable is the growth rate of the plants
- there are many different types of soil; clay, sand, chalk loam and peat

I will probably do number 2, as i have done more research on it, understand it better, and i don't know where i can buy universal indicator

SRP Ideas!

Hello :)
I've been thinking of a couple of ideas for my SRP and here's what I have so far:
-the effects of different types of soils on the growth rate of plants
-what type of plastic wrap prevents evaporation most effectively
-does the storage temperature affect the pH of juice

i was thinking of doing the last one, but I don't think i can buy universal indicator :s

then i was thinking of doing the first one, but i can't think of different types of soils other than normal soil. so i better get reasearching :)

Hello World