new and confused, in search for some help

[JD18]

Hi, tanks been set up for about 18 months, been going great, few problems while learning the hobby but about 3 days ago all my corals (mostly zoas, LPS and few acros) closed up 3-4 hours before lights out, had no idea why thought they were just having a 1 off as its happened before and is normal behaviour for some, thought everything would be fine by morning, all closed up still, thought later that day would be fine, came home from work and all were still closed so tested for high nutrients. Found 0.25 ammonia in the tank which wasn't a worry but >10 nitrate. Waited it out, tested again next day, 0.5 ammonia levels, >10 nitrate and around 0.03-0.00 phosphate. I did a 20L water change with the spare water I had. Yesterday tested all I elements I could thinking something else might be where it shouldn't.

salinity 1.025
temp 24C (75F) degrees
phosphate 0.03 or below
ammonia 0.5
nitrite 0
nitrate >10
Ph 8.0 - 8.4
alkalinity 7-8
calcium 450
magnesium 1450

You can see everything seems to be correct except for the ammonia. All my corals still seem to be closed up, torches and zoas especially, half of my hammers and frogspawns are closed up, mushroom fully closed but sps seem to be dong fine and open more than others. Haven't seen any pests on the corals and no signs on brown jelly. Checked both my starfish to see if one had died and is leaking the ammonia but both alive, (no other CC in tank other than snails all seem to be doing well). Only been feeding once a day since, fed twice a day for a few months, only 6 fish in tank. Really confused as why the ammonia isn't converting into Nitrate, it is API test kit for ammonia, nitrite, nitrate (could be bad test but only explanation I have for corals being closed as I'm not experienced enough). I haven't messed with flow speed or lighting.

Does anyone have any idea what might be happening and why, any ideas on how to fix. I am planning on getting water from LFS to do bigger water change but other ideas are extremely helpful. THANKS

 

[AydenLincoln]

Ammonia is high and that most likely is why. Make sure nothing died that could be causing this. Perform a large water change then add some bottled bacteria…and continue to test!

 

[Euphyllia97]

Ammonia is likely the reason. However big question mark where this ammonia is coming from :/ Would do some waterchanges until your bacteria are catching up.

 

[SPS2020]

Welcome to Reef2Reef!

Maybe have your LFS check the ammonia to be sure. Also, check the overflow and sump for anything that could be attributing to the spike.

 

[JD18]

Thanks for the replies, I have looked for anything that could be causing the ammonia but haven't found anything, all 6 of my fish are alive, both my starfish are alive. Only thing I could think of would be a large amount of snails all died at once? but from what I can see they are still alive and well. Would there be anything else that can cause ammonia to rise? I will be performing water change as soon as I can.