How much salt ?

I have the red sea salt, and on the bag it suggests 30g per litre of water which they recommend will give a salinity of 1.021. I thought this is a bit low and was thinking of 35g per litre. Does this seem right ??

 

35g per litre is correct, use a refractometer to measure, not a swing arm.

 

am i correct in understanding that salt and chemicals are best added slowly into the sump section of a tank, or would you add to main tank?

 

Salt should be mixed with RO water first, most things are just safer to mix with water first, like kalk and buffer. If you do regular water changes and use "good salt" you do not need to add to may things.

Yes slow is better.

 

Crispin, please do not add the salt directly to the tank or sump. You must first mix it up (with RO water) to the desired SG and ideally let is mix with a power head in the bucket for about 24 hours before use. Make sure it matches the tanks temperature before use as well.
Using a thin pipe, (not airline thin, 10 to 12mm should do) siphon out as much detritus and unwanted algae (if you had) from the main tank as possible. The reasion for the thin pipe is that it will give you more time to get around the tank. Also try to remove as much detritus from the sump area as well.
Once you have taken out the same amount as the newly make up water, you can simple pour/siphon the new water into the sump and turn the return pump back on.

 

Don't go by any recipe. Mix it with water before adding it to the tank and use a refractometer to measure salinity.

 

If you take the time to measure the salt in weight/water volume, it does save loads of time and messing around.