I would start fertilizing at 4-6 weeks or when the cotyledons dry up and fall off. They are what holds enough nutrients to get them through to transplant stage IMO but if you used a potting mix with fertilizer instead of seed starting mix then they should be good to go until planting out. Fish emulsion is normally mixed (depending on brand) @ 2 tbsp per gallon. The conversion for that would be 1-1/2 tsp per gallon for 1/4 strength. Personally I would use something higher in phosphorus for good root development instead of nitrogen for lush foliage. Top growth matters very little until after you get them in the ground or permanent home but with good roots comes good plants that can pretty much support themselves in good soil.

If even that. Keep in mind that there are only a few components on the System 2000 that are EK specific - the system manager and digital temp sensor are about it. Even if either one fails you're not totally out of luck. If the sensor fails the manager automatically goes into dumb boiler mode. If the manager totally fails there are temporary workarounds or a service board can be used to run in dumb boiler mode. Don't let anyone tell you that a replacement manager will bankrupt you either. Their trade-in program covers a good part of it. Any qualified tech, electrician, plumber, etc can purchase parts directly from EK and get Tech Support to help bring your system back on line. All burners except for a few older gas models are over the counter so obtaining parts is not a problem. I hope this helps put your mind at ease. You have one of the best heating systems on the market. With reasonable care it should stay that way.

Sounds like enough you have cleaned it as well as possible. Depending on where you are, some parasitoids that are native to Europe like the beetles and very specific natural enemy of the beetles but don’t bother native insects has been released for control of the beetles. So that may be one reason why you are seeing fewer of the beetles as well as the care you are taking to control them.

Communicating systems are just another level of a possible problem. This is how these systems are designed to be able to deliver the performance as to how they were designed. So if you go with a legacy thermostat the systems performance is no where near what it would be with the communicating thermostat. From your reply it sounds like you have a zone system, this is likely why they didn't include the thermostats as that zone board that controls your current system is not likely to work with the communication signal. This reason is partly why I chose Bosch inverter over the others as there is no proprietary signal to get it to work. I also have a zone system. It's not saying you can't have a zone system, just that the zone system will again be another proprietary layer of controls that cost more money to get the system to work as designed from the factory. The Lennox inverter does provide legacy control, so it's not to say that it won't operate with legacy control. However, from what I can see you give up some operational functions by doing so. Given this system is tied to a zone system / what those trade offs are isn't exactly clear. Communication has to do with algorithmic control. All the pieces communicate with one another, the unit knows the set point temp, the actual temp, humidity, temp outside based on all those inputs so that the equipment then can make decisions on 1% increments up and down, maintaining comfort levels. Non communication equipment like Bosch does things differently, the smarts are all in the outside unit. It knows out door temp then translates refrigrerant pressures / converted to temp as opposed to relying on a thermostat to "communicate" that info. The Bosch learns, constantly evaluating. The advantage in the Bosch is primarily no need for specialized controls to get the system to perform "as designed". It's typically not recommended to shop these kinds of things from a big box store as that box store is going to get a cut of the job. It might be in the realm of 10 to 20 percent of the job. If this company is willing to shyster costco out of their commission? What else would he do? I would continue to do some more home work if I were you. I service the Katy, Texas area.