day time PH crash

[Fragzilla]

hello,

I was wondering of I could get some help.

I've been running my tank since early this year and everything has been great up until about a month or so ago when I started seeing my LPS dropping off.

First a few Hammer (wall) corals started receeding then dying off, next a frogspawn (wall coral again), saw a few acans looking deflated, then saw some flesh coming away.

had to throw out 3 Goniopora corals and the 3rd Red ORA goni is also receeding and on its way out.

now my brancing Euphillias look very unhappy and not inflating.

I'm desperately looking for a fix for this as I've lost over £500 in livestock and it looks like im going to lose more in the coming weeks.

I've tested all params numerous times, cal 400, mag 1300, KH 9. Phos is 0.02 and Nitrate (no3) is 0.00

the only thing I notice happening is that when the algae scrubber goes off in the middle of the tanks day cycle, the PH drops significantly from 8.3 to 7.7-7.9

I know this is wrong but unless I have the scrubber on 24/7 I cant see any way around it.

Can anyone offer any advice?

I recently upgraded from a 23w bulb to a 45w eco lamp.

my scrubber is a cube shape design, all underwater with the lamp submerged in a tall jar, placed between the baffles in my sump.

algae growth is really good and nutrients are practically non detectable but im having issues. Can my scrubber be too effective? and stripping out to much NO3 or do you think my issue is with the PH swing and how can I rectify?

thanks in advance, I'm at my witts end and lm loosing my Mojo with the hobby fast...

:(

[SantaMonica]

Welcome from the UK.

I don't think pH is the issue. pH changes the same on many reefs, due to the photosynthesis of the periphyton, phyto, and seaweed.

Also, you cannot over-scrub, because scrubber use the same photosynthesis mechanism as the corals; when nutrients get low, it slows down.

However your bulb must be sealed somehow; maybe when you replaced it you got some sealant in the water?

[Fragzilla]

Hi and thanks for the reply.

I think I've found the problem now.

My scrubber was working so powerfully that it was stripping all the Alkalinity.

I did a largish water change with RSCP and Alk went up to 10DKH, tested it the next day and it had dropped to 8.2DKH

I've switched back to a 23W bulb and it's not stripping the Alk so much now, back to 0.5DKH drop per day which I think is Probably about right for my livestock.

I hope this fixes it anyway.

[SantaMonica]

You had said KH was 9, so I did not mention it. But if your scrubber is growing a lot, it is possible to reduce 0.5 per day for a few days.

Easy fix is to dose baking soda.

[Fragzilla]

I'm actually now convinced my lps has suffered just because I had zero nitrates for so long.

I'm wondering now on the best way to run the scrubber without it stripping all the NO3.

Do you think I should increase or decrease my night period to help do this?

I imagine decrease the night period, as it's been mentioned before that the algae does it's filtering in the night period.

I'm currently running off for 9hrs on for 15. I'm thinking 4 off 20 on will stop it filtering so much out?

[SantaMonica]

Well you went back to the smaller bulb that was doing good, right?

Nevertheless, I don't thing LPS problems are from over scrubbing. Softies maybe. Anyway you would just feed more to fix this.

Algae does it's filtering whenever the lights are on. It can absorb ammonia in the dark, but most filtering is in the light.

Something else caused this sudden LPS problem; I think it's something in your sealant that you used for the bulb. Or iron over-dosing.

[Fragzilla]

Hi

I think I may now be at the bottom of the problem.

Apparently with ultra low nutrient systems your supposed to run Alk at NSW levels as high Alk in a ULNS will cause Alk burns.

I wish I knew this before as I've been thinking it was due to low Alk.

I scrubbed the hell out of the scrubber anyway and letting the nutrients rise while the KH drops naturally.

Thanks for your help, with any luck I can now get my system back in recovery.

Hopefully won't be long till it looks like this again

http://i1378.photobucket.com/albums/ah104/nicktg2/C2C6B8E1-362F-4BBD-B749-662966F1C4D2_zpsditzbvei.jpg (http://s1378.photobucket.com/user/nicktg2/media/C2C6B8E1-362F-4BBD-B749-662966F1C4D2_zpsditzbvei.jpg.html)

Will need new hammer corals though :(

:)