lol, murphy is following you around
phos ban is good stuff. it works great for reducing elevated phos levels. i dont know about the seagel stuff though. phosban, i have used many times and keep it on hand incase i have issues but i only run it if phos levels are high.
if you use phosban, or any other, watch your alk levels as phosban can eat it up.
dont put it in your fluval. phosban is fine and soft. the flow within the fluval will turn it into dust and turn your tank orange.
get the RO/DI unit. you will not be cheaping out, it will pay for itself pretty quick. you will end up spending a lot more on other things dealing with this or that. for now, if can not get RO water, i would just use distilled water, instead of the spring, you can get it at most any supermarket.