Loads of people will say that doing that is bad for the goldfish but the goldfish ive got now ive had for 16 year and its still going strong and thats with doing exactly what your doing
i would like a bigger tank but feck doing all that with a big tank ya got these about 8 months ago for the kids they seem to be doing ok by doing this
have you got a pump and filter mate I've found bigger tanks a breeze too keep compared too smaller ones I prop do a little maintence about once a month and a quick scrub with the magnet once a week and change a bucket of water a week real easy with the gravel