Any time you silicon to glass a mark will remain forever. If you remove the overflows you may be left with lines where the overflows were. May be best to sell it, “as is, used, no guarantee”, so no one comes after you if something leaks after they go cleaning coralline with razor blades near the silicone.
I could go on and on about the controllers, but it is a personal choice and they do cost more then a couple of bucks. During that time you are super busy you can just whip out your cell and see your pH, temp, orp, and salinity are solid, so you at least know the tank hasn’t crashed an no one has died. If you start to tally the costs of timers for your tank, ATO, thermostat for your heater, pH controller for your Ca reactor, leak detectors and all that other jazz, it’s crazy to purchase them all first before buying a controller if you are even considering it.
Heaters crash tanks quickly, ATO can crash tanks quickly, stagnant water can crash tanks quickly. With a controller and a battery back up on your Vortex you have a good bit of coverage and will at least know you’ll be alerted if there is trouble. Temporary swings can stun animals a little bit, but quickly be recovered from if you act. Knowing is more then half the battle. I can go on and on, but I believe if you reread the stuff I’ve written in the past it will say most of what I have to say.
If you decide you are ready to take the plunge let me know and I’ll help you sort through the different parts you need and don’t need. One product Neptune sells, the IO break out box, would be a wise buy if they worked, but they don’t and are a POS. It is better to build one to get a higher quality product. It takes some time and materials and for me cost me more then buying one from Neptune, but I really didn’t like their’s.
You don’t need a controller to have a success full tank. I ran tanks for a long time with out them, but I also lost a lot of animals to over doses, salinity issues, and the big two heater failures and power outages. You have experienced tank crashes yourself and know it can take months to recover. For me it was a no brainier even during a time when I hadn’t collected a pay check in 6 months. I’m often the exception to the rule though.