Polyp recession throughout the week.

[cameron1]

My tank is definitely in a pretty good place right now but I’m a little confused about a trend I’ve been noticing with my coral. Every time I do a water change all of the corals look amazing the day after and then slowly recede their polyps throughout the week until the next water change. I was wondering if a toxin was being slowly released so I tried changing the carbon without doing a water change, but the coral still stays receded. Also, the water parameters stay about the same throughout the whole week and don’t seem alarming at all (no3 = 5ppm, po4 = 0.01-0.04 ppm, alk ~8, calcium ~420ppm). I’m seeing recession with my montipora and euphyllia mostly. Anyone have any ideas for what could be causing this?

[Jaren45]

what salt mix are you using?

[cameron1]

Tropic Marin pro

[Jaren45]

Okay I was just checking to make sure it wasn't a high alk mix or anything that could be causing issues.

 

Have you ever checked phosphorous in your tank?

[cameron1]

Gotcha. It usually tests around 7.6-8.0 so the alk is actually low if anything. 

 

what would phosphorous tell me that phosphate doesn’t?

[Clown79]

10 hours ago, cameron1 said:

Gotcha. It usually tests around 7.6-8.0 so the alk is actually low if anything. 

 

what would phosphorous tell me that phosphate doesn’t?

7.6 to 8 isn't low alk. Its perfectly normal level  6.5 or less would be low. Nsw level is 7

[empresto]

Size of tank?  Age of tank?  % of tank volume changed with each water change? Could be some trace element gets marginally replenished with a water change but quickly depletes due to your corals' needs.

[Clown79]

How are you mixing your salt water prior to use? 

 

Are you changing any filter media as well?

[cameron1]

11 hours ago, empresto said:

Size of tank?  Age of tank?  % of tank volume changed with each water change? Could be some trace element gets marginally replenished with a water change but quickly depletes due to your corals' needs.

It’s a 6 month old 40 gallon. I change about 15% weekly. Maybe I’ll get an ICP test done before and after a water change. I’ve never done one before

[cameron1]

1 hour ago, Clown79 said:

How are you mixing your salt water prior to use? 

 

Are you changing any filter media as well?

I mix enough for ~3 weeks in a large trash can with a small pump and then store it with the lid on. 

[Clown79]

1 hour ago, cameron1 said:

I mix enough for ~3 weeks in a large trash can with a small pump and then store it with the lid on. 

Do you use a heater to match the temp when you do waterchanges

 

are you aerating it with a pump before use

 

check that salinity is correct before use

 

What salt brand are you using? Some can only be stored for a week

 

The more detailed info you provide, the better we can help otherwise trying to determine cause is virtually impossible

[growsomething]

13 hours ago, empresto said:

Size of tank?  Age of tank?  % of tank volume changed with each water change? Could be some trace element gets marginally replenished with a water change but quickly depletes due to your corals' needs.

This sounds like the right track, since the corals perk up after water change.  Or an in-tank contaminant is being diluted.

I wonder how long they would stay happy if you did a 50% water change just once as an experiment, or if you ran some carbon for one week.

Could leathers or macro be causing recession by releasing chemicals?  I don't know if it's possible for them to effect stony coral that much.

[cameron1]

1 hour ago, growsomething said:

This sounds like the right track, since the corals perk up after water change.  Or an in-tank contaminant is being diluted.

I wonder how long they would stay happy if you did a 50% water change just once as an experiment, or if you ran some carbon for one week.

Could leathers or macro be causing recession by releasing chemicals?  I don't know if it's possible for them to effect stony coral that much.

I was also wondering if it was a contaminant. I do also change my carbon every week during my water changes. However, I know that it’s not the fresh carbon alone that’s helping because I have changed the carbon before without doing a water change (as an experiment) and the coral didn’t perk back up.  Maybe I’ll try a 50% change today. 

[mcarroll]

On 10/22/2021 at 8:37 PM, cameron1 said:

Also, the water parameters stay about the same throughout the whole week and don’t seem alarming at all (no3 = 5ppm, po4 = 0.01-0.04 ppm, alk ~8, calcium ~420ppm).

On 10/23/2021 at 1:49 AM, cameron1 said:

Tropic Marin pro

11 hours ago, cameron1 said:

It’s a 6 month old 40 gallon.

Water changes are spiking your nutrients low every time you do one.  

 

Feeding through the week restores numbers, but your corals feel it just the same....and recede through the week as a result.  

 

They need a break from your routine and they will be able to heal!  👍

 

Your no3 and po4 numbers are too close to zero for comfort....if you're doing anything for filtration, I would at least temporarily stop.  I would also stop water changes....and anything else that is removing nutrients from the system.  You can reassess once corals are growing well.

 

I would second the recommendations for dosing po4 if none of that applied for some reason....but it might be enough to simply stop doing water changes for a while.

 

BTW, that salt is known for mixing with a low alk.  Have you tested a freshly mixed batch to see what alk you're putting in during a water change?  (...and how that compares with tank levels.)   If you're also spiking alkalinity low (along with po4) at water change time then that's a double bad.  You should definitely confirm the numbers for the next batch of saltwater you mix.  👍🤞

 

(I would suggest TM's standard formula in spite of yours having the more apropos name.)

[Clown79]

8 hours ago, cameron1 said:

I was also wondering if it was a contaminant. I do also change my carbon every week during my water changes. However, I know that it’s not the fresh carbon alone that’s helping because I have changed the carbon before without doing a water change (as an experiment) and the coral didn’t perk back up.  Maybe I’ll try a 50% change today. 

Changing carbon weekly is excessive. This really should only be done when there is a need like when a tank has dino's.

[empresto]

@mcarroll, I'm curious why you think the water change is the stressor, as opposed to providing relief from the stressor, when the OP states that polyp extension is best immediately following water changes.  I agree with you that nutrient levels this low are cause for attention, but I would expect the stress to increase on the corals with each water change if nutrient deficiencies were the issue.

 

Not saying dosing NO3 and PO4 would cause issues, I just think there's more to this story.

 

[cameron1]

Alright I did a larger water change and there is still better extension the next day but nothing significant. I’m ordering an ICP test to see if anything is getting depleted over the course of a week/contaminants are rising. Might also start dosing NO3 and PO4 until I get to a better level. 

[mcarroll]

On 10/25/2021 at 2:35 AM, empresto said:

I'm curious why you think the water change is the stressor, as opposed to providing relief from the stressor, when the OP states that polyp extension is best immediately following water changes.

For one I see polyp extension as a neutral...just a reaction to the change in conditions...not something good per se.  

 

My *guess* as to the reason for PE in this case is that the corals are starving and reaching out hard to find every particle of food the can.

 

But mostly I'm just trying to be empirical.  🕵🏻‍♂️ 

 

There's nothing "relieving" about water changes per se, so I have to follow the clues to figure out what's going on.

 

The big clues:

1. New tank
2. Low nutrients
3. Signs that there's a LOT of "water cleaning" going on

For me those are an all-too-familar trio of conditions.  #2 and #3 clearly form a pair...one on the cause side and one on the effect side.

 

I have some additional anecdotal evidence from my dino thread on r2r: water changes during an already-low nutrient event can cause a variety of problems, including coral stress and mortality in some cases.  Water changes can be exacerbating.  So that's in my mind.  (Even tho there's no sign of dino's here so far.)

 

The OP's nutrients are super low....

 

This is especially true considering the tank's young age – where demand would be SKY HIGH and you'd want "a margin of safety".  (Eg. no3 ≥ 5 ppm and po4 ≥0.10 ppm)

 

Also, I don't know any reasons for coral recession that are more common these days than low nutrients – this is SOOOO true for young tanks like this.  

 

The other common reasons for recession like this, such as over-lighting or water toxicity, have no supporting evidence to suggest them.  (So far.)

 

On 10/25/2021 at 2:35 AM, empresto said:

I agree with you that nutrient levels this low are cause for attention, but I would expect the stress to increase on the corals with each water change if nutrient deficiencies were the issue.

There's often a time delay with something like this....generalizing, from 1-4 weeks would be a common interval between the event and the presentation of "associated symptoms".  It seems to work the same for positive or negative changes.....any damage you stop doing to a stressed coral might take a week or more to notice in the overall condition of affected corals.  This always makes diagnosis a little tricky as the evidence can seem to be a little deceiving sometimes.

 

On 10/25/2021 at 2:35 AM, empresto said:

Not saying dosing NO3 and PO4 would cause issues, I just think there's more to this story.

Very VERY possible.  

 

All we can do is formulate plans based on the current evidence tho...and keep waiting for the OP's next update to see if it contains any more clues that might cause other things to be considered. 😉

 

I actually missed commenting on the high-frequency carbon replacement....also definitely a potential stressor, if there's no (known) good reason to be using that much of it.  (None at all is probably the correct amount.)

[cameron1]

Everything lookin happy right now though!

[empresto]

@mcarroll, thanks for the detailed response!  I wouldn't have thought of polyp extension being a possible nutrient stressed coral reaction, but that makes a lot of sense since polyp extension is a feeding behavior.

 

I'll be curious to see what you find on your ICP testing, @cameron1