OH, Another thing, Michelle
Unless some toxic substance such as FANTASTIC, WINDEX, etc.., somehow got in the tank, I would never do 90%
water change.
Rather I would do small partial water change with AGED WATER few times in one day, especially when you have such odors come from the tank as you described.
Just remember,
chlorine is added to tap water to kill water borne pathogens. I really don't care what the MFG of Dechlorinator says, I had no problem using AGED WATER perculating with Air Stone or circulating via Power Head with Venturi Action.
If worried about metals, just have carbon filtration in reserve where metals will be removed by CARBON through ADSORPTION, not absorption.
I do remember talking and learning a great deal from few Old Timers (they must be in their 70's), they never used these products (chemicals) on the market with great sucess.
I once had 30+ tanks running at one time ( in 80's and single) where I crafted river system somewhat similar to Central System used in
LFS.
I build the rack so top most tank (RESERVE) is continuously SPRAYED into where there was vigorous Perculation and Heating. The water from the reserve will flow into lower tanks and so on and will drain automatically into sewerline. This is when I was breeding variety of fish. No, not the breeding tank itself. Breeding tanks were off the system (5Gal, 10G).
Only filters used in the river tanks wer simple sponge filters.
Sudden and drastic changes can be more stressful than the disease the fish is affected with.
One should always reason first before the action.
