# What's my pH



## X3NiTH (19 Aug 2014)

This isn't a I've got a co2 problem type of question, it's more of a calculation problem. I'm trying to get my head around some conflicting information I'm gathering and I know roughly what the pH for my tank should be but I need an independent analysis for correlation.

The tank is co2 injected and the water is RO remineralised with BeeShrimp GH+, EI dosed at 1.5x standard rate (APFUK kit), TDS 280 and assumed dKH of 0. With regards to the KH, I'm not adding any back but the snails may be donating it. Below is a picture of the tank with two probes, filter inlet (yup it's opaque with algae) and crucially a yellow/green drop checker that contains 4dKH, it's been that colour all day since lights on with stable injection and this afternoon the plants are pearling or what's left of them after a short back and sides earlier this week (I keep trying to tell myself it will look better in a week or so).

https://farm6.staticflickr.com/5595/14786390920_d1c5ae148d_b.jpg

So given the above information and the drop checker indicator colour, does anyone fancy taking a stab at what the assumed pH should be.


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## foxfish (20 Aug 2014)

Why don't you just test the PH?


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## X3NiTH (20 Aug 2014)

If you're referring to liquid test kits, I don't have any that go this low but maybe I should get a wide range one to test against, however I would still find it very difficult to gauge an accurate reading when the displayed colours in a narrow range are very similar.

As you can see I'm testing electronically twice evidenced by the pH probes in the water, they are both giving me different readings. One of them has always been in my tank and I have trusted that reading through observation of the drop checker and correlation with the charts (providing my correlation is correct), I put a second one in yesterday to test the unit and it's giving me a wildly different reading roughly 0.4 pH higher from the other.

Both probes have been calibrated with reference fluids, the blue one is the original and it is calibrated to pH7, the black one has been calibrated to both pH7 and pH4.01. Both probes remain calibrated and when the original (blue one) is placed in the pH4.01 reference fluid it read pH4.03 so a very near true reading of the reference fluid. Put the probes back in the tank after calibration and they produce different results, take them out again and put back in reference fluids and they have remained calibrated.

The conundrum is the new one reads higher than the other in tank and is slower to respond to change than the original.





The readings I am getting for a yellow/green drop checker (comparing with the cal aqua drop checker reference colours I'm beyond 30ppm co2) at 0dKH is 5.12 for the blue probe and 5.48 for the new black one. Which is the correct reading? There is a large piece of bogwood in the tank (been in water for 5 years and no longer stains the water) and there are 12 tetras in there so they may influence the pH downward a bit. There is also strong aeration in the tank in the form of a sintered stone blowing air in the opposite corner next to the filter outlet and the reading after 12 hours lights and gas off before the co2 comes back on is usually around pH6.6ish.

Head scratcher!


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## X3NiTH (20 Aug 2014)

Actually my Neutrafin pH test kit is the wide range one (5 year old kit), so I ran a quick test and here are the results.

https://farm6.staticflickr.com/5583/14792945190_6dbc5224d6_z.jpg

My eyes tell me pH6-6.5, another spanner in the works, maybe I should get a new kit in case the old one is duff.


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## ian_m (20 Aug 2014)

Why do you need to know your pH ?

You seem to be transfixed getting a pH reading ?

Your green drop checking indicates the CO2 level is fine. Plants generally don't care about pH.

Your test kit readings (and probably pH meter) will influenced by many other things than pH, especially in soft water. You are dosing EI, the salts can cause false pH reading.

I suspect this is why you are getting different pH reading from test kit and your two pH meters. All these are really designed to measure pH in absence of other salts and "stuff" that you have in your tank water.


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## X3NiTH (20 Aug 2014)

I'm giving the new UP pH controller from Karol a test run in comparison to the Weipro and I need to know which one is telling me porkies. I know that other things in tank influence pH including the salts. As co2 goes in the tank the Weipro will respond and when gassing/degassing equilibrium has been reached will dance around a +\- 0.01 variance and if I adjust the needle valve on the bottle I see the increase or decrease in pH due to the co2 a few moments later. The UP has stayed measuring at 5.48 while the Weipro read all the way to 5.10 and the fish were aligning themselves near the surface (potential gassing event very near), so I dialled down the gas a little and the Weipro responded a minute or so later and slowly climbed 5.10, 5.11, 5.12, 5.13 and is now hovering round the 5.13/5.14 mark, the UP still says 5.48?


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## Edvet (20 Aug 2014)

I think it is impossible to predict what the correct pH should be. The quality and make of the pH device (wet bulb, refilable, gel?) will make this difference. Sadly most consumer material is not lab grade material.


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## X3NiTH (20 Aug 2014)

I know, but I can't let a near 0.5pH variance between the two devices slide because in a tank with inhabitants if I was to walk away and let the new one control the gas based on 5 months of findings of the Weipro there'd be deaths, either the fish or the plants depending on whether I'm over or under injecting. I know the drop checker is my true guide but it's always late to the party when the fish are upset!


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## roadmaster (20 Aug 2014)

Fishes would be my guide independent of what device(s) say.
if you have already tried increasing the gas but fishes were uncomfortable,then what would pH reading really mean?


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## X3NiTH (20 Aug 2014)

It's not a problem with the tank it's a correlation issue between two devices aimed at planted tanks requiring co2 injection being controlled through measuring pH values.

Just to show that I'm not trying to fix a stagnant swamp here's the tank before I attacked the Glossostigma with scissors.


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## Edvet (20 Aug 2014)

Controling pH through CO2 is dangerous, fish don't matter what the pH is, as long as it is a "weak acid reaction", Fluctuating CO2 levels are BBA inducing. If you worrie about fish give less CO2 and reduce light or improve degassing. I only use my old pH controler only to give me a pH reading 24/7, CO2 doesn't flow through it


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## Andy Thurston (20 Aug 2014)

Just for the test and curiositys sake you could let one controller control the gas/ph level and take readings from both probes for a week then do the same for the other controller and compare the readings. Chances are both controllers are lying but my guess is the single point calibrated one is lying the most.


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## X3NiTH (20 Aug 2014)

I have been using the Weipro as a controller but only as a device to prevent fish deaths, I have the device set to turn of the gas only if the pH reaches 5.10. There's a 0.09 variance in the controller so with the set point at 5.10 it won't turn off the gas until it hits 5.01, at 5.00 all fish will be at the surface gasping, when the gas cuts off the co2 is driven off quickly by aeration. If the fish all decide to excrete at the same time and drop the pH to the cutoff value that's fine no harm done, maybe the plants get grumpy but if co2 reaches that value the fish will definitely be at the surface gasping.

I have strong aeration going 24/7 and I inject co2 to counteract this, at some point there is an equilibrium to gas injected and off-gassing through aeration, I have it all dialled in so I hover around the 5.2 mark all day from lights on, it's a little lower at the moment because I performed a large pruning of the glosso reducing the uptake.[DOUBLEPOST=1408551638][/DOUBLEPOST]Just to let you know I dialled down the gas a little earlier and the Weipro now reads 5.14 from 5.10 telling me I adjusted the injection rate, the UP still thinks it's between 5.47 and 5.48 and never moved.


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## X3NiTH (20 Aug 2014)

I'm going to run a profile between the two devices, so to this end I've put a camera facing the readouts and I have set the intervalometer on it to go every 2 minutes for 720 shots. The battery probably won't last that long but hopefully I can get the overnight degass period and the injection profile up until lights on.


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## X3NiTH (21 Aug 2014)

I managed to take 380 shots at 2 minute intervals before the battery died. The first shot was taken at 21:54 and the last shot at 10:37. So that's a little over 12.5hrs life out of a fully charged battery. I got the degas profile but I missed the injection stage which comes on at 11:30, I should have changed the battery before I left the house this morning. Useful information to know so I can rework the test to get the whole profile if I time my battery change right. So I'm going to re-do the test and I might try and stick a clock in the their next to the readouts so the information is more useful if I stitch the images into a movie.

The probes from what I saw of the degas profile are at least operating consistently even if they may both be wrong!

First image - (30mins after gas goes off)
Weipro - 5.21
UP - 5.54

Last Image - (tank totally degassed, stable reading for several hours before battery died)
Weipro - 6.50
UP - 6.86

Time to go and charge a few batteries!


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## Andy Thurston (21 Aug 2014)

Cant you just leave it plugged in?


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## X3NiTH (21 Aug 2014)

Big clown said:


> Cant you just leave it plugged in?



Leave what plugged in? If you mean the camera, I don't have the external AC supply and Nikons out of stock for the time being, so battery operation of the camera only.

If you mean the pH controllers, both are monitoring 24/7, the Weipro has control of the solenoid if the pH drops far enough to trigger it and if it does trigger the solenoid to close then the mechanical timer I'm using between the solenoid power plug and controller power port will be running behind time.


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## Andy Thurston (21 Aug 2014)

Yes the camera. I guess thats another extra i'll need when i buy a camera next week then.


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## X3NiTH (21 Aug 2014)

Have you decided on what you're getting?


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## X3NiTH (2 Sep 2014)

Here's a profile it's the longest I've managed to take so far, not the full 24hrs as the camera is being temperamental in not taking the full sequence I give it, I want 720 frames at 2 minute intervals and the vid below I managed only 680 (there's a firmware update that I need to upload to the camera that should hopefully fix this). I'll redo the profile once I sort the camera out.



My lights come on an hour too early for optimum plant uptake efficiency, for some reason that I can't remember I brought it forward an hour, I've set it back again to 1:30.


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