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Discussion Starter · #1 ·
Hi, I just got a new PH probe, placed it in my freshwater tank and had a reading of 14.0. So I filled a cup with tap water and it read 8.6. The probe hasn't been calibrated as I have no buffers. When I place the probe back in the tank it goes to 14.0 quickly which is the maximum the atlas circuit can read. After taking it out and putting it back in the cup of tap water it goes down to 8.6 and always does this. I haven't test the PH for months but when I did have a probe running it was ok.

So it appears I have something wrong with my tank and would like any thoughts on what's causing this and how to correct it.

In the last couple months something strange has been going on with the tank and probably related, there's always a layer of something on the water, sometimes its quite thick. I use a cup to skim it off but the next day when I go to feed the fish its back. Then out of the blue it'll be crystal clear for 2-3 days and the scum comes back.

I have Red Tetras, Dwarf Rainbows, Cory Pandas and Ghost Shrimp, everything seems to be doing good. Fish are always active and eat and no deaths for a long time. The tank is 125g, soil, planted and been running almost 2 years. There's been a lot of growth over time and lots of plants cut out so the soil is full of roots. The tank has 2 large canister filters and I do 30%-40% water change every 7-10 days. I just did an ammonia and nitrite test which both are good. I'm out of nitrate solution so couldn't test it.
 

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There is no way your tank has a pH of 14. It would literally etch your glass.
I once made a bottle full of basified plant matter and forgot about it. It ate a hole trough the glass. And that was maybe pH 12.
 

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Thanks, I had a feeling it couldn't be that high, its odd every time it touches the aquarium water it goes over 14 but tap water it doesn't. It seems to always respond the same.

Does this make sense?

When ph probe is in aquarium ph is over 14.0, when probe is in a cup of aquarium water ph is 8.2.

So I shut the power bar off which has lights, heater, air pump and 2 filters. Ph then drops to 8.2 with probe in the tank.

Then I turn the power back on and it goes back over 14. So then place the probe in a cup of water and place that in the aquarium, ph is 8.2 so its nothing in the air.

Then I unplug the heater only and the ph drops to 13. That's the only piece of equipment with power going into the aquarium but the more equipment I unplug the lower it drops.

Any ideas?
 

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Well it would seem some current is passing through the tank.
What was wrong with the old probe? I know the pen meters go crazy if you don't store them correctly.
I need to get a new one as I let mine dry out... it is even crazier than yours.
 

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Discussion Starter · #6 ·
I let the other probe dry out. I didn't have that probe in the water much because the cable was to short.

I agree it seems like current is affecting it but kinda strange it's still there when no motors of any kind are in the tank, only a foot of tubing for an air stone and the in/out for two filters, yet when everything is unplugged ph is good. :surprise:
 

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moisture on surfaces of light fixtures etc, may be leading the current in a path that is not expected.
Here is a slightly dangerous test... If you have a multimeter, take a wall plug and measure for both AC and DC voltage between the tank water and the earth/ground pin on the plug. Please don't accidentally touch live or neutral.
 

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Discussion Starter · #8 ·
Everything is dry. For the test do you mean put the ground probe in a ground on the power bar and then the positive probe touch the water and see if there is any AC or DC volts?
 

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Yes, even though you don't have a direct connection, it is possible the current stems from induction.
See what happens if you pull the heater from the water.

I just want to check, you are only running air pump driven filters? and the heater?
 

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First, there is no way your tank is at 14 pH. I don't think even soda lakes are that high and not much, if anything, can survive at those levels.

If I could recommend a safer test, get a grounding probe for the tank, I've seen them on line for under $20. If that brings your pH probe to its senses, then you found the cause. The next step would be to find where that current is coming from. My guess is that one of your electrical toys is not grounded properly. Find it by the elemination and fix it. Having an electrical current in the tank is not good to anyone.

Another quick test is to plug your strip into a GFIC outlet and see if it trips.
 
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probes are know to go bad to.
 

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What you said indicates some sort of current leak whether it's direct or inductive is irrelevant. You really need to quit thinking about your pH probe and consider your personal safety. This is nothing to play around with. Putting your hand in this tank under the right conditions could literally kill you! Is your pH really worth it?

Install some sort of GFCI protection whether it be a GFCI outlet or adapter. Then you can figure out what is going on safely. Seriously! Address this problem first before doing anything else.
 

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Discussion Starter · #13 ·
Nordic, same results with heater out of the tank and yeah I'm only running 2 canister filters, air pump and heater.

OVT, yeah it turns out my PH isn't 14, no doubt about that. I'm getting the reading I'm expecting when the water isn't in the aquarium. I don't have a GFCI but I'll probably pick one up. I'm going to see if I can make a ground probe but the strange thing is there are no toys in the tank, no wires go into the tank but some do run up the back of it.

Rob in (ca), I don't think its the PH probe, something power related is definitely going on in the tank to cause the readings to be high.

Zorfox, I'm not so worried about me, I understand power a little bit and don't see my exaxt issue as a problem to me, but with that said I'm going to solve it because it isn't safe. I'm more worried about my fish, what are they feeling?

Last night I put the heater back in but unplugged and today the ph is reading 10.9, so its better but still a bit there. I'm going to try a different outlet for the power bar and go from there. As most of you know its not an easy job, things are tight and no moving 125g tank.
 
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