When is dose thoroughly mixed

[hkgar]

If I add two ounces of Randy's ALK to my sump, how long do you think it will take to have completely dispersed through out the system so as to get an accurate (as accurate as a test kit can be) reading of the new ALK level?

[swk]

Depends on the amount of flow you have. But I would think after 5-10 min it would be adequately dispersed

[hilgert]

The answer is..."it depends." And much of the "it depends" is determined by exactly where you add it (do you add it right before the return pump?), as well as the turnover rate of both the sump (determined by the effective gph return of the return pump) as well as well as by the turnover in the tank (how much water volume is moved around in the tank by *all* pumps, powerheads, etc.). The longer you wait the more confident you can be that it is mixed consistently throughout the system. Personally, I would not test before 15 minutes had passed.

Is this a one-time correction, or something you will be doing daily? Adding that much to your system all at once can create a noticeable change in pH (depending on which of Randy's two recepes you are using). If you have dosing pumps for Alk/Ca then you could use your Apex (which I see you have) to add that in small increments instead of all at once.

[bertoni]

In my 29g tanks, it took 10 seconds or so. For larger tanks with sumps, a longer period might be required. What's the flow rate to your sump, and what's the actual water volume in it? That'd probably be the limited. I'd expect the tank to reach steady state in less than a minute, given the common flow rates we see.

[hkgar]

Flow rate is 851 gph and sump has 26 gallons and DT is 180 minus air space and rocks and sand.

Oh and I usually add it the first chamber (return FROM the tank)

[bertoni]

I'd wait five minutes, personally, and try testing. If you're worried, you could try another test a bit later to check for mixing.