PH Low - CO2 wont cut in - Where should I look?

[Aftica]

Hello Tom;

I have a problem and need some direction...

My tank seems to be doing fine from a plant perspective I suppose... here is a fast pic I just snapped... (not a quality pic - just a fast snap) The tank has been running now for about 2 years.

OK - out of my tap and aged, my water is

• PH 7.8
• KH 3.9ºdH
• GH 5.6ºdH

I have no real algae growing except some in amongst the Java fern on the piece of wood... and the fish (Discus, cardinal tetras, Corries, and a bristlenose) are doing fine and have been in there now for the full 2 years+. I have NOT vacuumed the flourite (ever) so there is I am sure a lot of mulm down there.

Ok - I just tested my tank water... and at the moment it is....

• PH 5.5
• KH < 0.56ºdH (ie < 10ppm)
• GH 6.0ºdH

OK - so needless to say the PH controller is not kicking in, and growth is slow. I am running an air-stone 24/7 at the moment... I tried running searches here at planted on dropped KH and PH etc.. but the search won't let you use "PH" and "KH" as terms as they are too short... (or I was unable to figure out how to do it)...

So I would rather NOT be fishing out the fish... but I think a gravel vacuuming is going to be required... any suggestions as to a good course of action to get this back on track?

The basics of the setup is: 77 Gallons - 3 WPG GE 9325 lamps - 100% Flourite substrate - Eheim Pro II 2028 - Eheim Ecco 2231 - Eheim Surface Extractor - Coral Life 9W TurboTwist UV Sterilizer (lamp 2 years old) - Pressurized CO2 system - Aqua Medic Co2 Reactor 1000 - Milwaukee pH controller and regulator.

Shhh... Yes I have cross-posted this over on .plantedtank.net... sorry up front if that crosses some etiquette rules...

 

[Frolicsome_Flora]

Ok - I just tested my tank water... and at the moment it is....

• PH 5.5
• KH < 0.56ºdH (ie < 10ppm)
• GH 6.0ºdH

Are you sure?? a KH of 10ppm??

If that were true, your water would be super saturated with CO2, a KH of 35ppm/PH 5.5 produces a CO2 content of about 190ppm. I think you might have typo'd or misread your test kit.

 

[Aftica]

Nope - it's right less than 10 ppm (Hagen Nutrafin kit) - did the test twice - its a pretty simple test kit and 1 drop gives me yellow.

I don't think the standard co2 chart applies here - there is something else affecting the KH / PH which throws the chart out the window I think. (I am assuming the excess mulm that is in the bed... but not 100% sure)

I used to keep the tank at a PH of 6.8 with the controller... which used to give me a CO2 amount somewhere around 35 to 28 ppm roughly... and was rock stable for a long time... I always had the small airstone running in the back on a small rena mini air pump but only ran it at night and only for 1 hour at a time via a timer (on and hour - off and hour, etc..) as I found sometimes the fish needed a little surface agitation... not a lot... but during the day never on... the plants I found were adaquate oxygen.

 

[Frolicsome_Flora]

Yeah, I have the same test kit and find it to be pretty good.

Weird, do you have anything else altering the PH other than CO2 content?

Theres no way (that I know of) that anything could be altering the KH of the water short of removing elements such as a carbon filter, its much more likely to be something altering the PH which is throwing all the calculations off.

Just seems odd that you have a GH of more or less your standard tap water, but a KH figure thats totally whacko by comparison.

Id be really interested to see whats going on. Have you tried a different PH and KH testkit? Just to make sure?

 

[VaughnH]

You can always test your test kit by making a known KH sample of water. It isn't easy, but if you have an accurate gram scale and an accurate volumetric flask or beaker you can do it. 4.99 grams of sodium bicarbonate, that has been dried out in the oven at about 250F for a half hour or so, mixed into 5 liters of distilled or DI water, gives a 40 dKH solution. Mix 10 percent of that with 90 percent distilled or DI water and you have a 4 dKH solution.

 

[Aftica]

I got to say I never went that far to check the kit... but the kit does test my tap water at KH 3.9ºdH (about 100ppm). I tested my friends tap water with it as well (he has a different kit from me - a Red Sea one) and his results were very close to the same as mine... so I think the kit is reasonably correct.

 

[Mooner]

... so I think the kit is reasonably correct.

I thought the same about nitrate test kit I was using. Whipped up a test solution and was I shocked!!!!!!!! The kit in question wasn't even close. I did find another kit which tested (calibrated).

If you are serious about testing you must calibrate your tests... or not, it's up to you

 

[Aftica]

I really think the odds of both kits being "off" by the same amount to be rather highly unlikly.

I thought the same about nitrate test kit I was using. Whipped up a test solution and was I shocked!!!!!!!! The kit in question wasn't even close. I did find another kit which tested (calibrated).

If you are serious about testing you must calibrate your tests... or not, it's up to you

 

[Frolicsome_Flora]

It would be unlikey, but if we're to trust those reading, all your fish would be dead from asphyxiation, or close to it. So its worth checking the readings against something.

If you have nothing else that will alter your PH, other than CO2, then somethings a-miss.. your readings imply that your KH reading is off, especially seeing as your GH is more or less the same as your tap water readings.

 

[VaughnH]

It doesn't pay to trust the KH/pH table to give accurate ppm of CO2 in the water. My experience has been that nearly always the table gives a much too high reading. I used to run 80 - 120 ppm routinely, based on that table, while I actually had low CO2. Much better to get a drop checker, use known KH distilled or DI water in it, and rely on that for measuring CO2. The KH of the tank water is interesting to know, but unless it is way out of normal range it isn't a real concern. (except for the few plants that grow only in low KH water)

 

[Frolicsome_Flora]

I have one of those Vaughn, but Im not sure that Im using it right. If I use tapwater in it, I guess I can go by my water report on the KH of it.. its just the KH that theyre telling me is pretty scary, 19.95 English Clarke Degrees, which i work out to be about 16 degrees, which is nearly 7 degrees higher than my test kit reads.

 

[VaughnH]

The drop checker doesn't give any better result than just measuring the KH/pH of the tank water if you use tap water in it. The "secret" for success with the drop checker is using water with nothing else in it that affects KH or pH except bicarbonate and CO2. And, that means using distilled or deionized water. The grocery stores in my area all sell gallon jugs of distilled water, for about a dollar a gallon, so that is an easy thing to use. Then, by adjusting the KH of that water by adding sodium bicarbonate (baking soda), to 4dKH you make the solution in the drop checker turn green at 30 ppm of CO2, right where you want it.

 

[Frolicsome_Flora]

ooo that sounds a great idea, i can buy a litre of battery topup water which is just distilled water for very little. Ill definatly do that, my KH test kit seems to be light years away from what the reading actually is. Using a nutrafin KH/GH kit, cant beleive just how far out it is.

Thanks Vaughn

 

[Frolicsome_Flora]

Then, by adjusting the KH of that water by adding sodium bicarbonate (baking soda), to 4dKH

Ive tried to do a bit of maths *covers eyes*.

Am I right in thinking that you would need 71mg of bicarb to achieve 4dKH? which is about 1/8th tsp? (the only measuring device I have)

Im prolly really wrong lol but its worth a try. Ill just blame the calculator

 

[VaughnH]

Add 4.99 grams of bicarbonate of soda, after drying it in an oven at about 250F or whatever the lowest setting of the oven is, for a half hour or so, to 5 liters of distilled water. That gives you 40 dKH water. Then mix 10 ml of that 40 dKH water with 90 ml of plain distilled water. That gives you 4 dKH water. With this you can calibrate your KH test kit, as well as load a drop checker.

 

[Frolicsome_Flora]

Excellent, thanks buckets Vaughn Ill try that tomorrow

 

[Sintei]

Add 4.99 grams of bicarbonate of soda, after drying it in an oven at about 250F or whatever the lowest setting of the oven is, for a half hour or so, to 5 liters of distilled water. That gives you 40 dKH water. Then mix 10 ml of that 40 dKH water with 90 ml of plain distilled water. That gives you 4 dKH water. With this you can calibrate your KH test kit, as well as load a drop checker.

Question:

Why bother drying it in the oven? Is there so much fluid in it it will affect meassurment?
Ill test it in my lab tomorrow if i get time for it..

 

[aquabillpers]

Add 4.99 grams of bicarbonate of soda, after drying it in an oven at about 250F or whatever the lowest setting of the oven is, for a half hour or so, to 5 liters of distilled water. That gives you 40 dKH water. Then mix 10 ml of that 40 dKH water with 90 ml of plain distilled water. That gives you 4 dKH water. With this you can calibrate your KH test kit, as well as load a drop checker.

Flora's declining KH could also be caused by plants that consume the bicarbonate ions, like vals. I observed this in a tank that was severely overpopulated with jungle vals - the KH, when replenished, again disappeared in a matter of days. (Someone named Vaughn posted about a similar problem at APD last year. )

An alternative would be to purchase another KH test kit, although the one that she has has been "validated" against two different water systems and one other test kit. If the new kit confirmed the prior tests, then something definitely is "eating" KH and should be removed, or, alternatively, bicarb should be added to the dosing schedule.

Bill

 

[VaughnH]

The world is full of aquatic plant growers named Vaughn. But, I do recall that post too.

 

[Tom Barr]

Gievn the wide variety of user error in KH measurements, I've asked Greg at SeaChem if they might be so kind to make a reference KH solution that is accurate to less than 1ppm for the hobbyist.

I've not talked directly to him, and I'll also address the pH and Ammonia Alert items they make and see if they might do a similar thing with a nice color scale for better accuracy and sell it for 20-30$ etc, which ios about what the drop checkers run.

They should pay me huh?
But if it helps the hobby, and makes things easier for the hobbyists, it's not an issue for me.

Seachem gives a lot to the hobby, so I have little issue with it.


Regards,
Tom Barr