what is happening with my tank every two weeks?

[reef tank 2.0]

I am noticing a reoccurring event every two weeks with my tank. I don't understand why...

I do water changes every two weeks. (1st/15th of each month) sometimes a day or two early/late, depending. every month, when that water change day is coming close, my corals seem to WAKE UP. Some are fluffier than normal. Some have more movement than normal. Once I do the water change, they seem to go back to "normal", and the process continues to repeat itself. Over the past year of having the tank, I haven't had any parameter issues, everything is stable, but their appearance seems to change right before water change time. I haven't ever let it go longer than the two weeks, but should I? I held off doing the water change last night, but will be doing it tonight.

I also notice I get some soft red/brown algae on my overflow, more aggressive than when i do the actual water change. that seems to be an ongoing issue, but its nothing crazy. I'll scrape it off, net it out, and we're good for a few days. but I notice the algae on the overflow is a little thicker and more wide spread towards the two week mark. I don't let it go too long before scraping it off. I don't have this algae on the rocks, sand, or glass. it's only on the overflow. it covers the overflow from top to bottom.

I'm trying to keep this vague since I am not trying to isolate any problems per say. I don't understand what this two week/pre-water change time frame is doing to the tank and corals. little nervous to extend that water change time frame, but it certainly makes me wonder what good/bad it would do

since you'll want to see my parameters, here are my parameters at day 15 (1 day after scheduled water change day)

ALK - 8.5
CAL - 450
MAG - 1200 (this dropped from 1275 a week+ ago)
PH - 8.2
PHOS - Yes, can't tell the exact number (.1-.25, light light blue)
TRATE - 10.8

 

[BryanM]

I can take a guess, but you'll need to do more water testing to verify possibly.

Is it possible that right before your water change your Nitrates and Phosphates are higher, and that your critters like this "dirtier" water?

 

[reef tank 2.0]

well, the parameters that you see above were taken about 30 minutes prior to this thread.

i could try to push it out another wek and then monitor and re-test, but that makes me nervous.

 

[JTP424]

I am thinking the same thing @BryanM said.
Do tests right before your change. And then the day after.

Also may want to check your rodi tds, just as a safety check.

 

[JTP424]

What kind of filter systems are you running?

 

[Tahoe61]

It's still a fairly new tank right?
Try doing WC once a month.
What saltmix are you using?

 

[reef tank 2.0]

@JTP424 - my tds reads 0 on the 3rd stage output (output going to mixing station). I am running a 75GPD - 4 stage unit. (I assume you were asking about water filtration). I also have a skimmer going, skimming more on the drier side.

@Tahoe61 - the tank is coming up on a year old, beginning of March. I am using RC

 

[bakbay]

What is it that you're trying to solve? I've skimmed through your build thread, the tank looks great! Things are not dying and progressing nicely. Given you have little/no coralline algae or SPS, your alk consumption should be negligible. Fish load is light so N&P should be kept in check.

I agree with @Tahoe61 above -- why not change your water once a month, unless you enjoy doing it? Corals just started to acclimate to the water and you "reset" it? As for WCs, I hate doing them! My SPS tank (also cube like yours but slightly bigger) hasn't had a WC since it was wet 4 years ago.

Good luck!

 

[reef tank 2.0]

what is it that I'm trying to solve? I have no clue. I just don't understand why the corals are happier as time goes on (dirtier water). I mean, I COULD let it go longer, but that makes me nervous. I would definitely need to test more and keep an eye on my parameters. maybe i skip water change tonight and let it ride.
Wouldn't letting the water changes go, promote further algae growth?

i honestly don't mind water changes. I open the drain valve in the basement at the sump, water empties to the drain. close the valve, turn the pump on and fill it back up with a hose. It takes as little as 7-10 minutes depending. Does take a little longer if i decide to do extra cleaning. but since it's all in the basement, it makes it easier. I do skim the sand in the display tank every once in awhile. Most of the work is in the basement.

 

[JTP424]

Dirty water is coral nutrients!
Maybe drop the amount of water you change out

 

[reef tank 2.0]

that leads to high parameters and fish/inverts dying. (like how i immediately went to the worst case scenario?)

I currently swap out 40 gallons of water every two weeks (150g total volume)

 

[JTP424]

If you have a decent cuc algae shouldn't be an issue.

 

[JTP424]

Id you keep your water that clean you're going to keep having those cycles
Id work my way down to 20 gallons and see what happens.
If you don't like it. Go back to 40.

 

[WeirdBeard]

Unless I missed it, you don't say how much WC you do. 10%, 20%, more?

I believe every action with a reef tank should have a purpose. Even things that we take for granted as necessary like water changes. So, the question is why are you doing water changes at all? Is it for nutrient export? Is it for keeping trace elements up?

If you try to answer those questions, you might rethink when you do it and by how much, and you might also answer the original question you posed.

 

[reef tank 2.0]

i am definitely lacking the CUC's. I had about 10 snails at one point. My hermits killed the majority of them. I do have a few astrea snails still, and about 6 bumble bees. all my ceriths are gone. I know I need to restock. That is definitely on my to do list this week or next.

 

[reef tank 2.0]

@WeirdBeard - I currently swap out 40 gallons of water every two weeks (150g total volume)

why do I change the amount of water I do and why so frequent? heck if I know. When I had my last tank, I followed the same schedule and water amount. Something I've always done. I never changed the water based off my parameters. Sounds like im throwing money away now that I think about it. In my mind, clean water, means happy fish/coral. I stopped testing my water all the time because my parameters never changed. well, I guess that's because I never gave it a chance to.

 

[reef tank 2.0]

i was learning from a local well established reefer when i first started. It was his recommendation about the water changing schedule....so I followed it. I stuck to it. Everything was working, so I didn't steer away. Maybe now I decide to experiment. Hoping things don't go south in a hurry

 

[JTP424]

i was learning from a local well established reefer when i first started. It was his recommendation about the water changing schedule....so I followed it. I stuck to it. Everything was working, so I didn't steer away. Maybe now I decide to experiment. Hoping things don't go south in a hurry

If you're worried about quick problems, start slow. Drop a gallon every so odten until its where you want it.. Next week do a 39 gallon change. Do those for a bit. Then go to 38. Etc

 

[reef tank 2.0]

as long as the parameters are in check, is that my biggest concern?
from the parameters in the OP, Magnesium is the only one that seems to have dropped in the two week time frame. if the parameters change, other than Nitrates and Phosphates, what other parameters could cause me problems if they were to decrease?

 

[WeirdBeard]

@WeirdBeard - I currently swap out 40 gallons of water every two weeks (150g total volume)

why do I change the amount of water I do and why so frequent? heck if I know. When I had my last tank, I followed the same schedule and water amount. Something I've always done. I never changed the water based off my parameters. Sounds like im throwing money away now that I think about it. In my mind, clean water, means happy fish/coral. I stopped testing my water all the time because my parameters never changed. well, I guess that's because I never gave it a chance to.

A 27% water change is quite a lot imho for normal WC without some kind of emergency, especially without any defined purpose. I'm far from an expert, but IMHO what tanks love even more than clean water is STABLE water. Stability is the name of the game in my limited experience. Try lowering that water change to 10%.
If you really feel like you need to be changing out that much water, try doing a weekly 10%.