bleaching sps

[killinit123]

I have a scenario I would like some insight on. I have multiple different monti's and also multiple different acros and millis. i have a 75 gallon rimless with 36 gallon sump/refugium. my lighting is 2 ocean revive so26's full spectrum LEDs. I also do weekly 10% water changes which i do every Sunday using reef crystals. so my issue is that towards the end of the week my monti caps start to bleach out.. just my monti caps any encrusting monti or any of my arcos or millis do not do this.. I just recently got test kits for calc, mag and alk but have not used them yet. I dont think that lack of nutrients is the case tho because wouldn't all of my sps start to bleach and not just the caps?? I'm not sure if monti caps have different requiremts in nutrient levels related to encrusting montis or acros and millis? if so then lack of nutrients may be the culprit because every week when i do water change the day after the monti caps look healthier than ever. I'm just not sure what is going on here any input would be fantastic and thanks in advance. when i get home tonight i plan on testing all levels so i will post that when after i do. but in the meant time any ideas would help a lot thanks again.

[PhaneSoul]

Are you cleaning the sand when you do waterchanges? Growing any algae? Reactors or other equipment, chemicals, ect. Are the polyps still coming out?

What makes you think it's a lack of nutrients and not the other way around?

[killinit123]

Are you cleaning the sand when you do waterchanges? Growing any algae? Reactors or other equipment, chemicals, ect. Are the polyps still coming out?

What makes you think it's a lack of nutrients and not the other way around?

yes i do clean the sand when i do water changes but i have course aggregate on top and sand on bottom.. no algae growth and no reactors just protein skimmer and i use kalkwasser in my ATO thats the only thing i dose per say. yes polyps still extend very well and just the monti caps start to bleach towards the end of the week. the reason i feel that is is a lack of nutrients is because whenever i do a water change the caps color back up after a day which makes me think there was a lack of nutrients to cause it to start bleaching. they also show very good growth which is weird.. all other nutrients are zero amonia-0 nitrate-0 nitrite-0 po4-0 temp 78-79 ph-8.1-8.3

but what im stumped by is the fact that the acros and millis do not do this and i thought that they are more sensitive to nutrient levels thats why none of this makes sense to me

[DivingTheWorld]

You're dosing but not testing. I'd recommend you start testing, specifically Mag, Alk and Cal. Good color following a water change could indicate that you're replenishing Mag, Alk & Cal. Never dose what you're not testing for.

[outssider]

You're dosing but not testing. I'd recommend you start testing, specifically Mag, Alk and Cal. Good color following a water change could indicate that you're replenishing Mag, Alk & Cal. Never dose what you're not testing for.

+1
this is what I'm thinking too !

maybe your kalk is not keeping up !
when you do the water change, your cal and alk are replenished somewhat. maybe time for regular dosing.

[killinit123]

You're dosing but not testing. I'd recommend you start testing, specifically Mag, Alk and Cal. Good color following a water change could indicate that you're replenishing Mag, Alk & Cal. Never dose what you're not testing for.

+1
this is what I'm thinking too !

maybe your kalk is not keeping up !
when you do the water change, your cal and alk are replenished somewhat. maybe time for regular dosing.

I agree that i should be testing and i just got my test kits and working crazy hours havent had the time to test. I'm just confused as to why its only my monti caps specifically that are doing this?? if in fact calc mag and alk are being depleted towards the end of the week why are my more sensitive sps not showing any signs of bleaching also? I wanted to test last night but i did not get home until late so i will try to test tonight and post an update to try and figure out exaclty whats going on