ph crash

[discusdean]

hi all hope every one okay was wondering if there was anyone out there that could help me as my pride and joy 220g reef is having a moment my ph has started dropping at night to 7.45 and not getting above 7.7 -7.8 during the day have tried looking for reason but cannot see the wood for the trees i think

amm undetectable
phos undetectable
nitrite as low as my test kit goes
nitrate as low as my test kit goes
mag 850-870
calcium 360-375
hardness 12
temp 26 c (chillered )

any help or ideas would be gratefully recieved as some corals not opening and getting worried

 

[cheeks69]

Causes of Low pH Problems

As described above, low pH problems are those where the pH is below about 7.8. That is, where the daily pH low drops below 7.8 for any portion of the day. Of course, if the pH reaches a low value of pH 7.9, aquarists may still want to raise it, but the need is not so immediate. Several things can commonly result in low pH, and the solution to each of them is different. Finally, there's nothing to prevent a tank from having all of these problems simultaneously!

The first step in solving a low pH problem is to determine why it exists in the first place. Some possibilities include:

A calcium carbonate/carbon dioxide reactor (CaCO3/CO2 reactor) is in use on the aquarium.

The aquarium has low alkalinity.

The aquarium has more CO2 in it than the surrounding air due to inadequate aeration. Don't be fooled into thinking that an aquarium must have adequate aeration because its water is very turbulent. Equilibrating carbon dioxide is MUCH harder than simply providing adequate oxygen. There would be NO change in the pH between day and night if equilibration of carbon dioxide were perfect. Since most aquaria have lower pH during the night, they also are demonstrating less than complete aeration.

The aquarium has excess CO2 in it because the air in the home that it is being equilibrated with contains excess CO2.

The aquarium is still cycling, and has excess acid being produced from the nitrogen cycle and degradation of organics to CO2.

http://www.reefkeeping.com/issues/2004-09/rhf/index.php

 

[cheeks69]

The Magnesium seems to be very low it should be around 1200 I would check that test or have the Mag measured at the LFS. Are you dripping Kalk ? How much total tank turnover do you have with all pumps and ph's ?

 

[docklink]

You would be amazed at how much your pH can change by getting an exchange of fresh air into the environs of your tank. I was fighting the same thing recently, went for several weeks adding supplemental Sodium carbonate solution to try to bring the pH up though my alk was staying close to desired levels. pH kept dropping down to 7.6 . Then it dawned on me that the house had been closed up due to the temp dropping outside. An afternoon with a couple of windows open brought the pH up to 8.2 without any other intervention. I didn't think it could have "that" much influence, but it obviously did.
I do second cheeks on the Mag levels.

 

[Woodstock]

How are you measuring your PH? monitor? Is it calibrated? low batteries? If you're using a test kit, check its expiration date... and get a second opinion on your readings.

With that said, indoor co2 can be very high especially in the winter months if you use gas appliances. An indoor co2 monitor/alarm would be a good idea for you and your family. Also,as suggested above, open a window near the tank to allow fresh air into the area. Let us know how it goes!

 

[Jerome]

what's your akalinity at? PH and ALK are mutually exclusive.

 

[mattie]

i like the idea of second opionions
i'm assuming your hardness is the german DKH value which would be a little high for the amount of calicum in the tank and the mag was a little low
most of the time when you add buffer's it stablesize's the ph like kent super buffer
if you are driping Kalkwasser your calcium uptake may be to high for the way you are mixing it which would give you a higher Alk and a lower Ca then being balanced.
what has worked for me is adding a capfull of white distilled vinger per 5 gallons of kalkwasser. this prevents precipitation in the mix and boost calicum and raises ph all at the same time.
test the dissolved oxygen in the tank becouse cheeks is right about the co2 in the tank
another thing it could be is if you are also having an algae problem at this time a surplus of algae with the lights off produces alot of co2 in the water

just thowing some good ideas out there for ya

 

[discusdean]

cheers guys sorry not been on for a few days not well but just to tell you about the tank a little more the reef is 225 gallons at present with a high calcium demand due to a large amount of hard and soft corals.i do have a aqua medic 1000 reactor running usualy but stopped this when the oh started to lower incase the co2 injection was to cause (to no avail). have a turn over of around 12 times an hour.Have also had the water checked at the lfs with very simular results.not started adding kalkwasser jet was thinking that it was my last resort to raise ph.i do have a full electronic control system that i have fully calibrated and all were nearly perfect to the best of my knowledge. my lounge is airated fairly well with all vents open permanetly. ah. ah. god this is frustrating in awnser to mattie the only algae i have is a thin layer of dust on the glass as runn elima phos 24-7.

 

[discusdean]

excuse the spelling should read before posting