are ph monitors really that accurate

[gobie]

I recently bought an American Marine Ph monitor to set up and run a calcium reactor on my 75 gal reef tank. calibrated monitor everything seemed fine tested my tank ph read 7.75. Mixed up a new fresh batch of salt water and got the same reading so bought a new brand of salt and still the reading was the same. buffered my tank using seachem buff and cracked the calcium out of solution when the monitor read 8.03. American marine told me that there monitor couldn't be wrong if it was calibrated right so I went out and bought a new calibration packet and it was only off by .2 on the 7.0 calibration fluid so I also bought a ph test from slafert with this test my ph read 8.0 if not better. dkh at 10 temp 72 salinity 1.023. after the calcium bust in my tank I lost all of my invertebrates from snails to shrimp and also crabs due to ph shock. monitor read 8.3 salfert read 8.6. did 100% water change to bring starfish and corals back everything is rebounding my monitor now reads 7.89 and things look better. after 9 years doing saltwater tanks this was my first reef set up since march of this year I've only used regent tests this is my first expierence using a monitor I dont like it and I dont trust it. Ive always trusted my tank chemestry ultimately by on how the animals look, and using regent tests. does any body have any suggestions.

update: thank you all who have posted info on this the problem was the probe
not out of specs just at the very far end of spec I replaced with a new one and problem solved. @ 6 am ph8.27 thanx again

 

[Ed Hahn]

I recently bought an American Marine Ph monitor to set up and run a calcium reactor on my 75 gal reef tank. calibrated monitor everything seemed fine tested my tank ph read 7.75. Mixed up a new fresh batch of salt water and got the same reading so bought a new brand of salt and still the reading was the same. buffered my tank using seachem buff and cracked the calcium out of solution when the monitor read 8.03. American marine told me that there monitor couldn't be wrong if it was calibrated right so I went out and bought a new calibration packet and it was only off by .2 on the 7.0 calibration fluid so I also bought a ph test from slafert with this test my ph read 8.0 if not better. dkh at 10 temp 72 salinity 1.023. after the calcium bust in my tank I lost all of my invertebrates from snails to shrimp and also crabs due to ph shock. monitor read 8.3 salfert read 8.6. did 100% water change to bring starfish and corals back everything is rebounding my monitor now reads 7.89 and things look better. after 9 years doing saltwater tanks this was my first reef set up since march of this year I've only used regent tests this is my first expierence using a monitor I dont like it and I dont trust it. Ive always trusted my tank chemestry ultimately by on how the animals look, and using regent tests. does any body have any suggestions.

I think you should sell it to me for $50 bucks :lol: . I am just kidding. Do you have a Refugeum that runs opposite of your tank photo period? You Ph usually swings at night when your lights are off.

 

[DonW]

I like the Pinpoint monitors. You do need some way to check if your getting a funny reading (test kit). You should also let the new probe stabilize in your tank for a day before trusting the reading. The solution can NOT be cold for the calibration. I think the temp should be 72 if I remember right. As far as your tank goes I would slowly raise you SG and your temp to 1.025 or 35ppt and at least 78.

Don

Don

 

[NaH2O]

I agree, Don. Check the temperature of the calibration fluid. The back of the fluid packets show what to calibrate the unit to at given temperatures, so make sure that is correct. Also, did you calibrate it with 2 fluids? I think it's 7 and 10?

 

[flamehawk7]

I had the same problem as you when i first set up my tank. it was a new set up and i bought the same ph monitor , i thought this thing is going to be the ticket.i put it in and i got a ph of 7.8 i was like how could this be . i called american marine, i was very happy after talking to those guys . they told me in a new tank a ph of 7.8 to 8.0 was real common and to just keep an eye on things. watch for large swings in ph , nitrites and nitrates and to watch my ammonia. he also talk about electrical interference, to rule that out use batteries instead of the ac adaptor. as my tank aged my ph came up to 8.2 to 8.4 i might add that is without adding bottled goods. i do also have a small refugium and i think that helps as well. i have learned that if the animals look healthy and you have been doing you maintenance don't react to fast to numbers, think then act i hope i was of some help mike

 

[NaH2O]

flamehawk7 - good post! Low pH is often found in new cycling tanks....mine included. I'd have to look back at my log, but I believe it was 7.8 for some time. Thanks for also touching on the point of interference effecting the pH monitor. Someone had commented on that recently, and I never realized it was an issue. The one thing that is confusing with gobie's problem is the test kit is conflicting with the pH monitor, so the question is, which is right? Calibrating these monitors can be quite a task....turning those little screws.....more than an hour later it is finally calibrated (at least for me....I'm a perfectionist).

 

[dgasmd]

When you calibrated it, did you do a two point calibration with the 7 and 10 pH solutions or just the 7? That could be your problem right there. pH probes need to be calibrated to two solutions to be accurate. Also, was your probe well sealed witht he soft cap they come with? It could certainly be a bad probe too.
I've had one of these monitors for about 3 years and I couldn't be happier. However, they do require calibration once per month or every other month. You should always coorelate your pH to something else to make sure you don't take action based on faulty readings.

 

[gobie]

thanks to all for help, I took my monitor to Aquarium Paradise (guys been around 12 years) come to find probe was faulty. not faulty but with in spec. but at the far low end so new probe things are great. ph reads 8.27 @6 am this morning.

 

[flamehawk7]

NaH2o imagine that a perfectionist in this hobby..................hummmmm im willing to bet us reefers suffer from a few of those medical tiles out there A D D , addictive behavior, ect . after all what would my life be like if i had to sit still and could'nt spend money on my perfectly maintained fish tank. as for the ph monitor, i would trust those calibration fluid long before i trust a dry test kit that is subject to how well i follow instruction.