First, your deck is not ruined so you can rest easier knowing that your project is salvagable.

For future reference or for new readers building decks you should always clean and prep your deck before sealing regardless of whether it is sanded ot not. Restore-a-Deck is a two part kit made for this type of prep.

Another thing to consider is that using a clear sealer is not your best bet for two reasons.. One is that the wood will turn gray as there is no UV protection or sunblock if you will, in a clear sealer. You need some type of pigmentation to absorb and/or block UV rays. The second caveat of a clear finish is that any discolorations in the wood, especially if not cleaned before sealing will be made that much more noticeable.

Never go above 80 grit sandpaper when doing a deck. It will cause more problems with sealer penetration. I use 60 grit all the time and never have any issues. One has to keep in mind this is an outdoor surface. The goal of trying to achieve the finish of an interior hardwood floor is not only extremely difficult it is impossible to maintain. You make certain tradeoffs of beauty for the sake of longevity. I have introduced the Baker's Gray Away line of sealers which is outstanding for softwoods like cedar. It is a conditioning oil that pentrates and keeps the wood from getting damamged by UV rays and water penetration/evaporation cycles.

If this were me, and considering the time of year (not sure in which region you are located) I would keep what is on there and redo the projects in the spring. The Restore-a-Deck cleaning kit's step-1 will emulsify that clear coat (as long as it is oil based and not an acrylic water borne) and allow it to be washed away. You would probably need to apply a second coat of the cleaner to penetrate deep into the wood and remove those stains and dirt burried in the wood. You would follow with a step-2 pH balancing agent and your cedar will look fresh built and the pH enviroment will be perfect for applying a penetrating sealer. No matter what product (stain sealer) you go with make sure it is a penetrating oil based product.

Hope this helps.

hjb1,

You will not be satisfied with a cedar deck in the long term. The cedar these days is not the old growth stuff of years ago. It is not naturally rot resistant and not naturally insect resistant. In my opinion is is way too soft for a deck surface. Nobody would ever use cedar as a floor inside the house. What makes it acceptable as a floor outside of the house? I don't mean to upset you but you are in for an up-hill maintenance nightmare.