Maelgrim Posted February 4, 2007 Report Share Posted February 4, 2007 New tank 2 weeks into cycling. PH was 8.2 when first setup. Now it is 7.8. So got an Alkalinity test which is showing 9.9DKh. I thought that the high DKh would mean the PH would resist lowering. Any thoughts appreciated Quote Link to comment Share on other sites More sharing options...
suphew Posted February 4, 2007 Report Share Posted February 4, 2007 It could be your test kit, but that reading isn't that low, testing PH can be a waste of time, it will swing during the day anyway, mine sits round 8 when the lights are off and moves to 8.3 during that day Quote Link to comment Share on other sites More sharing options...
Maelgrim Posted February 4, 2007 Author Report Share Posted February 4, 2007 Yeah I tested twice just in case, both times in the afternoon with lights on, so I would have thought it would be higher. Quote Link to comment Share on other sites More sharing options...
tee-em Posted February 4, 2007 Report Share Posted February 4, 2007 My tank is newly established and found similar issue, I have a marine aquarium encyclopedia that states this is normal for a new tank. Make sure your other water parameters are correct.... ca, mg, po4 etc Mine slowly started coming right and ph slowly increased after a month or two. Quote Link to comment Share on other sites More sharing options...
lduncan Posted February 4, 2007 Report Share Posted February 4, 2007 I thought that the high DKh would mean the PH would resist lowering. Any thoughts appreciated Alk resists changes in pH. The actual pH is also a function of the partial pressure of CO2. Basically if the ambient CO2 level in the room is higher than normal (which can be common), then the pH will be lower for a given alk. Also the 7.8 you measure, may not be the actual pH. And don't be too concerned about chasing pH numbers. Quote Link to comment Share on other sites More sharing options...
wasp Posted February 4, 2007 Report Share Posted February 4, 2007 A night time reading of 7.8 is fairly common. Shouldn't be that low during the day though. My own tank was getting that low at night so I took steps to ensure it never went below 8.0. This resulted in noticeably better coral growth. Main thing make sure you have plenty of aeration, as pH is a function of alkalinity against Co2, so you need the aeration to keep the Co2 in the tank as low as possible. Quote Link to comment Share on other sites More sharing options...
hazymranch Posted February 4, 2007 Report Share Posted February 4, 2007 In a new/cycling tank, the high concentration of dissolved organics in the water column will also make the water acidic. Don't get too concerned about your water chemistry until after your tank has fully cycled as it will swing all over the place as the different spikes occur and bacterial and algae species bloom and recede. Give it a solid 2 months before you even measure the pH. Quote Link to comment Share on other sites More sharing options...
Maelgrim Posted February 5, 2007 Author Report Share Posted February 5, 2007 well I think I have the problem then. Aeration. I have removed the sump (to add some baffles), its been out a week meaning no Skimmer or overflow (just so powerheads running). I will recheck the PH once the sump has been back in operation for a few days. Thanks Quote Link to comment Share on other sites More sharing options...
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