Its not rust, like has been previously said. Its just old dried algae from the cleaning magnet, so dont worry.
I'd go for sand mate, Ive just changed from gravel and it was a nightmare! So make the right decision before you fill up if you are planning on a planted tank.
Where in the UK are you? Look for your nearest 'Maidenhead Aquatics' they are the best! Also, the guys at my local one (polhill garden centre) are really switched on and will give you some great advice on the day of you buying your plants.
I'd go for sand mate, Ive just changed from gravel and it was a nightmare! So make the right decision before you fill up if you are planning on a planted tank.
Where in the UK are you? Look for your nearest 'Maidenhead Aquatics' they are the best! Also, the guys at my local one (polhill garden centre) are really switched on and will give you some great advice on the day of you buying your plants.

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