1.021 is a little high for the Fig 8's, I believe they prefer a light BW of about 1.005 - 1.010. The GSP's will do well at 1.021 (you can go full marine with them with no problem). I have seen it recomended to NOT mix GSP's and Fig 8's for a permenant set up, the GSP's get too aggressive and usually take out the Fig 8's eventually.