I'd have to agree with that as float switches/solenoids/pumps are all unreliable. Because I did not trust this method I ended up going with a LiterMeter III setup. I use LiterMeter base module w/ pump attached, remote pump, and water exchange module.
- Base pump used for top off (1 week of dialing in evaporation rate and you don't have to worry about this anymore)
- Remote Pump used for drain to house drain.
- Water exchange module is used for new saltwater and water exchange module will kick it off if it goes above a certain level in sump.
As an additional safe measure my float switches are just a failover and not really used for top off but rather a second preventative measure. Low water alarm will actually kick off return pump and outlet to LiterMeter III and e-mails me so I can access the situation. High water alarm will kick off LiterMeter III outlet and I have a bulkhead installed at top of sump should both of the above failsafes fail which drains to house.
The LiterMeter III pumps have amazing delivery/draw heights so that is not of concern. Each pump can do a total of 99 liters (26) gallons/day so in Steve's 400 gallon system you could do up to 45% water changes in a week

(With my 1000 gallon system it will meet the needs too and is still able to do 18% water changes a week which I doubt will ever be that high) The pumps also take this set amount you want to change water and divides it over 150 times a day so when you talk about stability, this is one of the best things you can do to a system IMO to stabalize parameters. (Ask yourself if doing a 15-25% water change does not change water chemistry outside of the measurable tests we perform?)
That being said, this is just my opinion but at retail price of $683 for all three pumps and main module, 5 year warranty, they are the best upgrade I've ever made to my system. I recently rebuilt the pumps with new tubing before putting them back to work but this was just proactive maintenance and I was not having any issues with the pumps. Randy Holmes Farley also does a similar method and recommends this 'continuous water change' method over anything in our reefs.
LM III Manual
***Sorry for any derailment or rant Steve:ape: