hammer coral not opening..possibly kh too low the cause?

Hey..newbie here.



275l tank,up and running over a year as a fowlr and a hitchhiking mushroom coral.

Ammonia 0.

Nitrites and trates at 0.

Phos was just slightly up due to a top up of tank water but did water change yesterday using ro water.

Cal is 420.

Mag I don't have test for yet..

Kh..my problem.. Should be 120..it's 50?!

Ph- just under 8,possibly a little lower,hard to tell matching up colours to cards.



So I bought a hammer coral (unaware of kh) and it came out within 4 hours,big and beautiful with great colours. Ffwd a few hours and it hid,receded into the skeleton. So I thought maybe the lights are too bright (it came out when lights went off again) so I moved to shade under rock,it started to reappear almost instantly then it dropped straight back into itself.. Flow is low so I don't think that.

Then I checked water tests again and realised I hadn't checked kh, got a shock when expecting to add the 12 drops to 120ppm and instead only added 5 before it turned so 50ppm.

Is this the problem with the receeding hammer?

My plan is tomorrow to head to marine shop,I need mag test as am I right in thinking with kh that low,mag will be?

What can I do about kh? Marine buffer of some type?



I believe it's the levels in the salt I'm using,more for fowlr tank not reef tank but I have a whole pot of it so I need to use that first. Can I buffer for now?

Thanks I'm advance..