Substrate change?

[classic-chassis]

Currently i have black pebbles with goldish stripes runing through them. I thought it would look good with the gold of the fish (first tank set up) but I now realise with the black background it does'nt. In fact it makes my tank look too dark.
I would like to put white sand in but I would like to know if this is possible with fish in the tank.
It may sound stupid but please remember I wouldn't own an RTG if i never forund this site and asked a stupid question about Aros and 55gal tanks, so be kind.
Obviously I realise i can't just take out the pebbles then dump a massive aqmount of sand in.

 

[aro-lover]

You will need to clean your sand really well with the boiling water. Wash the sand nice & clean before introducing it to the tank when you are sure it would not pollute the water.

Instead of dumping entire sand at one go, I would suggest to introduce it in phases.

 

[meanbestorque]

its possible to change substrate with fish in water. for taking it out, i used a large but fine net. placing substrate back in is a little more difficult. I dropped the water level 50%, then added the substrate to one side of the tank, then slowly evened it out

 

[meanbestorque]

... or another method would be to use a container with a lid. load the container with the sand and cap it. place the container in the tank, let it sink to the bottom, then open the lid and gently pour the sand out.

 

[classic-chassis]

I've decided to try some lights with a higher K number first. I believe you need to allow bactiria to pass from old substrate to new, and sand needs to be stirred wich sounds like hard work. I need depth of about 1.5 in because of the way may tank is built, (no double sheet on bottom, just 1/2in braces).
The lights I have now are only 57K, I'm goingto increase them to 1400K (or is that too much?). I figue if the light is strong enough it will highlight the goldish stripes in the pebbles.