Is my potting mix okay?

Depending on water capacity of the 'sea soil mix', you probably need more perlite or similar. did it already have some perlite in it? can't assume these things and i've never even heard of that brand. coc only needs 2 parts coco to 1 part perlite to have an 'ideal' gas:water mixture in the volume. In higher water capacity substrates you want up to 1:1 parts soil and perlite, or 50%. If it already had some perlite, do some algebra and solve for X. that'll tell you how much to add next time. if you already have rooted plants in it, less than ideal will still work fine more times than not. don't do anything crazy trying to adjust it after that point. An adjustment before a transplant would be wise, though. You can re-use soil, sure. It's smart to get the roots out and understand that some of the nutrients that existed in it was used up... not so much if just seedlings, of course, but if it was an entire grow you may need to re-amend or fortify it unless you want to treat it more similar to a soilless medium and just provide 100% of nutrient needs through fertigation. when i first started i used some FFOF for 3 grows before i threw it out. I ddin't even bother to remove the old roots, lol. Did i get lucky? Maybe. Better to be safe than sorry. Just because it 'can' work doesn't mean it doesn't carry elevated risks. if you had any rootzone issues related to microbes, i'd avoid re-using it. could cook it in the oven? lol, but then your home will smell liek shit and probably poison yourself with wahtever shit condensed on the interior your oven, lol. you want some potash with those baked potatoes? you really, really don't.