Using chemicals to destroy algae isn't the best method out there. It's a temporary fix, if it even works.
Most, if not all, of them are safe for fish. Some are safe for plants too, although they're rarely safe for inverts. So if you have shrimp/snails, they'll probably die off.
If you decide to use them however, dosing ferts will depend on what algae you have. If your algae is due to excessive fertilization, then don't dose ferts or reduce dosage. Most of the time, algae is due to not enough co2 and too much ferts. If you dose XX amount of ferts for XX amount of gallons, as recommended in some dosing sites, then you need the proper amount of co2 to help plants absorb all those nutrients dosed. If you don't have enough co2 to help the plants process the light, that helps them take in nutrients, then you're looking at a lot of nutrients in the water column going unused and algae ends up taking advantage of it.
In any case, dosing chemicals to remove the algae can potentially kill off the algae for the time being but if no tweaks and changes are made, they will just grow back in a matter of time.
I would suggest you identify the algae you have, find the source of its growth (whether it's lack of co2, too much light, lack of nutrient, whatnot). Then tackle it that way by correcting what you're lacking or having too much of. This will help you out in the long run by eliminating that algae from your tank forever (or until an imbalance occurs again). It will also protect your inhabitants from being exposed to chemicals.
Going the "All Natural" way is always the best ;-)
To eliminate the current algae, use flourish excel. Inject it at the algae sites to kill them off. It should help you "restart" the war as you fix the problem.
