Setting fert levels for an autodoser for some macros/trace

Bob - I'm not going to comment on the amount to dose. But just ask that you consider the two options...

One is "EI" variety - that is to take your normal weekly dose (added up) and spread it across each day. As with EI, that means you are accepting a wide swing of values between the day before water change, and the day after.

The other option is what I think of "level dosing". That's where you have a target level that you are trying to fix. So that means a fixed dose each day, EXCEPT you apply a "gap" dose after water change to bring the tank up to the level it was before the water change - instead of waiting the entire week to rise to that level.

In your case though, with your daily partial water changes - I'd suggest that the latter is not appropriate, and that you should use the former.

Thanks Steve. I'm definately going EI, though I may back off the amounts if issues pop up. So far so good. All is auto now on the 90 gallon. I am going to experiment with Tropica and with Flourish and see if that yields improvement over CSM+B, which I expect it to.

I won't be dosing at full strength of the EI as there are a couple of extra days in the cycle to keep the pump from cavitating. It is now setup for 21 days before I recharge. I have yet to black-out the container but will tonight to keep the traces from deteriorating. And also I am going to set up an identical system on the 65 gallon.

I am also contemplating doing a 1x per week 40% water change, but let the fill cycle take about 4 hours on and off - to allow the heaters to keep up. Then one to two more 12% WC change per week. Still haven't decided if I want to go this route, but at least its an option.

On both tanks I'm still going to dose PO4 manually, for a while.