The water is cloudy because it's a new tank. Keep feeding down and do lots of water changes and it should go away on its own when things settle down.
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If you get a basic model gravel cleaner like the one in the following link, it will let you clean the gunk out of the gravel without having to remove the gravel from the tank. You can buy them from any pet shop or make them from a plastic drink bottle and a garden hose, (see details below for home made gravel cleaner).
Aquarium cleaning should take 30 minutes every two weeks. Learn how the professionals do it in 18 easy steps.
www.about-goldfish.com
You put the gravel cleaner tube in the aquarium and have the end of the hose in a fish bucket. You can suck on the end of the hose for a second to get the water syphoning down the hose, or you can fill the gravel cleaner tube with tank water and lift it up. As soon as the water starts draining down the hose, put the gravel cleaner tube back in the tank water, and start gravel cleaning. When you put the gravel cleaner back in the water, keep the open end up so air can come out, otherwise the air will stop the syphon.
When water is draining out of the tank, push the open end of the gravel cleaner into the gravel and push it down to the bottom, then lift it up. As the water drains out it sucks the gunk out of the gravel and removes it from the tank with some of the water.
You move the gravel cleaner around the tank systematically cleaning the gravel as you go. When you have drained out some water (say 50-75%), you stop gravel cleaning and remove the gravel cleaner from the tank. Then fill the tank up with dechlorinated water.
It sounds complicated but if you ask a pet shop assistant to demonstrate it, you will see it is very easy to use.
I have added a couple of YouTube links below that show 2 different ways of starting a gravel cleaner. The first video shows a young lady using a gravel cleaner with a one way valve in it. This allows the water to go out but not come back in. The second video shows a guy filling the gravel cleaner and hose with tank water and putting his thumb over the end of the hose. He then puts the hose in a bucket and the water starts draining. They are both different to the way I describe and are other options.
If you see a gravel cleaner that has a narrow plastic end on the gravel cleaner tube, remove that bit because they are completely pointless and not necessary. Just get a basic gravel cleaner like the one in the first link above.
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HOME MADE GRAVEL CLEANER
You can make a gravel cleaner from a 1, 1.5 or 2 litre plastic drink bottle.
Cut the bottom off the bottle and throw the bottom piece in the recycling bin.
Remove the cap and plastic ring from the top and throw those 2 bits in the recycling bin.
This creates the gravel cleaner tube.
Then get a length of garden hose or clear hose from a hardware store and stick one end into the top of the bottle. Find a hose that fits in nice and tight so it doesn't come out easily. Most 12mm garden hoses fit in perfectly.
That is a home made gravel cleaner.