Do lots of water changes or leave tank alone?

[DesertReefT4r]

...... I wouldn't do this just yet. Do you know what your Alk level is when mixing up a new batch of Salt or are you going off of what is on the box saying it mixes at 8-9? If you have a salt that mixes Alk really high, something like Coral Sea Pro. Then you dont want to mix salt and add. If you do this you are only exacerbating the issue and causing your Alk to spike even further. If on the other hand your new salt mix, does mix Alk lower then you will help dilute that current Alk of 11.

You are better off just leaving it at 11, because this isn't bad. My suggesting would be to pull your Kalk drip offline and lower your Alk slowly over the next 30-45 days or longer. Since your tank is mainly SPS with Acro frags it may take you awhile before your Alk starts coming down on its own.

As for Kalk dosing, this is more than likely what has caused your spike in Alk. My suggestion would be to not use Kalk until your parameters are more in line and just showing a swing in the downward trend. Since you have frags you dont need to chase PH. You want to keep your Alk stable month over month for Acro's and they will start growing. You have taken them out of a system they were acustomed to. Then plopped them into your system that more than likely has different flow, different parameters in water and lights. Not until those Acros get settled in and have stability once again will they start growing.

When you say in the past you used to run Alk 8-9, how long ago was this? This spike, in your Alk, how long has it been running 11dkh?

It looks like your Phosphates have gone from Zero up to 2.5ppm starting in August. Then was high for almost 30 days. Then has dropped pretty rapidly down to almost Zero again. What changed during this time to cause the SPIKE? Then what did you do to get it to drop so quickly?

Good advice. Take it slow and let things drop on their own. Nothing good happens fast in a reef tank.