Po4 Drop, how fast is too fast?

[splix]

Short story: downsized tanks, Po4 was around 0.3, over the next few weeks got it down to around 0.1 using hanna test. Bought out a guys tank and I guess his po4 was way high because the 30ish pounds of LR I brought in from his tank, my po4 shot up to 0.5. Went on business travel, wife was home feeding normal, po4 was 0.75 when I got home. Tried bringing it down with water changes but by the time it was time for another WC, po4 was back up. I decided to start No3Po4x. Slowly ramped up the dose over 2 weeks. Things were looking good, po4 was slowly dropping. It went from 0.78 to 0.68 in the 2 week ramp up without any water changes. I was now at my max dosage of no3po4x of 4ml for my 70g tank. I went on a vacation so feeding went to minimal with the auto feeder. I got home, things looked....ok. Some zoas were closed up, nems looking a little shrunken in but not looking horrible. Tested Po4 at 0.35. So I dropped Po4 by minimal feeding and dosing No3po4x all week by 0.3 ppm. I'm pretty sure this was way too fast. I dropped by no3po4x dosing back down to 3ml/day from the 4ml it was on.
I tested No3 at 10ppm before I left. I've not tested yet for the vacation return number.

Was a 0.3 ppm drop in Po4 too quick in a week?
Tank: 70g softies. BTA's, zoas, mushrooms, leathers. Only coral not looking 100% are a few heads of zoas here and there closed up. Anemones are not 100% normal size, I'd say they're around 70%.
alk - 8.5
calc - 480
mag - 1350

 

[najer]

I would say that was fine for the corals you have, keep testing in case you need to lower the dose more.

 

[Randy Holmes-Farley Verified Community Expert]

Was a 0.3 ppm drop in Po4 too quick in a week?
Tank: 70g softies. BTA's, zoas, mushrooms, leathers. Only coral not looking 100% are a few heads of zoas here and there closed up. Anemones are not 100% normal size, I'd say they're around 70%.
alk - 8.5
calc - 480
mag - 1350

I doubt there will be any serious lasting issue.

I think it is probably best to think about the limits of the drop (or percentage remaining) and not just the range. A drop from 1 to 0.7 ppm over a week is likely not a concern. A drop from 0.30001 to 0.00001 ppm in a week probably is.

In any case, I'd just continue on and observe.

 

[splix]

I doubt there will be any serious lasting issue.

I think it is probably best to think about the limits of the drop (or percentage remaining) and not just the range. A drop from 1 to 0.7 ppm over a week is likely not a concern. A drop from 0.30001 to 0.00001 ppm in a week probably is.

In any case, I'd just continue on and observe.

Makes sense. I went ahead and did a 25% water change and kept the dosing at 3ml down from 4ml. We'll see how it goes. The plan is once it gets to 0.15 I'll start tapering off to hopefully around 1ml for maintenance.