Ph Started Crashing

[Macko1968]

I'm currently doing a fishless cycle on a Trigon 190 tank. Progress was good initialy but yesterday I noticed my ammonia was static & a check of the PH showed it had crashed from mid-7s t 6.4. I did a water change & brought the PH back up to 7.4. 12 hours later it has dropped back to 6.4 again.

I only have silk plants & a resin cave in the tank, along with a sand substrate. Any ideas why I'm experiencing a crash, given that my other two tanks went through a fishless cycle without a hitch? Also, is there anything I can do to stabilise the PH during the remainder of the cycle?

cheers

Mick

 

[Bobtastic]

Hi Mick,

You can add bicarb to bring up you pH whilest doing the Fishless cycle. I'm sure someone will ask you what the stats of you tap water are so I may as well get there first.

I understand that it is usually the GH/KH readings that have the biggest affect on pH stability. The lower the KH the more likely it is for the pH to change, the higher it is the more stable the pH is when more chemical/etc (ammonia/nitrites) are being added.

 

[waterdrop]

Hi Mick,

Since you are fishless cycling (and definately don't have either fish or plants) and since you've already experimented once with a water change and the pH has dropped right back down, I'd say its a safe assumption that your total alkalinity (if you used a KH kit) is zero or one and that it would be reasonable to use bicarb to buffer the water.

Please understand that plants don't like the sodium this will leave behind and it can cause more rapid changes in KH than is advisable for fish, so this is just something to do during fishless cycling and must be discontinued once you make the big water change and have fish!

Here's what I'd suggest: Make sure you have a large enough box of pure baking soda (sodium bicarbonate) (usually from your kitchen cabinet) prior to when you plan to do the water change. Do a 90% water change (always good for beginners to -practice- doing their gravel clean when doing this, even though they don't have fish yet.) (Small water changes have no meaning when you don't have fish of course!) After you refill with conditioned, warmed tap water and have recharged the water to 4-5ppm ammonia level, then add the baking soda. I'm assuming your Trigon 190 is one of those 190 liter corner tanks so I'd add about 9 or 10 teaspoons of baking soda to the 190L - its all very rough, so it doesn't have to be very exact.

You should find that this will hold your pH closer to your tap level for a much longer time. You can simply repeat the process some weeks later if pH eventually drops again. If this turns out not to be enough baking soda and its drops again quickly and you are getting frustrated then you could bother to get a KH liquiid test kit and that will give you more precise information, but really, in your current situation, you could probably get by without it and save the money.

~~waterdrop~~

 

[Macko1968]

Thanks very much folks. Water changed, ammonia added, bicarb added, fingers crossed.

 

[OldMan47]

Uncross your fingers and wrap them around that test tube Macko. You will want to know how well you did with the ammonia and the bicarb dosing.

 

[Macko1968]

36 hours after doing the water change & adding the bicarb & my PH is a steady 7.6, sames as from the tap. Also 5ppm ammonia is cycling down to 0 in @ 18 hours.

Thanks again for your help folks.

 

[waterdrop]

With that amount of bicarb I'd expect it to stay rock solid for at least 3 days or maybe a week or more. As I said in the post up above, keep an eye on the pH. When it starts to go down, it may go down more slowly because of the bicarb but at some point you'll want to catch it before it drops low enough to greatly slow the cycle. I think you can get by without a KH kit. What a KH kit shows you is a number, say 1 to 10, and if it sits at 4 or above then you know pH isn't going to move, but once it gets below 4 you know pH will be dropping pretty soon in a cycling tank, so it serves as an early warning.

~~waterdrop~~

 

[LionessN3cubs]

With that amount of bicarb I'd expect it to stay rock solid for at least 3 days or maybe a week or more. As I said in the post up above, keep an eye on the pH. When it starts to go down, it may go down more slowly because of the bicarb but at some point you'll want to catch it before it drops low enough to greatly slow the cycle. I think you can get by without a KH kit. What a KH kit shows you is a number, say 1 to 10, and if it sits at 4 or above then you know pH isn't going to move, but once it gets below 4 you know pH will be dropping pretty soon in a cycling tank, so it serves as an early warning.

~~waterdrop~~

so its normal for the KH to drop as well? My KH had been at 4 after adding the seashells, tested last night and its a definite 3...guess that means I should keep watching the PH then

 

[waterdrop]

With that amount of bicarb I'd expect it to stay rock solid for at least 3 days or maybe a week or more. As I said in the post up above, keep an eye on the pH. When it starts to go down, it may go down more slowly because of the bicarb but at some point you'll want to catch it before it drops low enough to greatly slow the cycle. I think you can get by without a KH kit. What a KH kit shows you is a number, say 1 to 10, and if it sits at 4 or above then you know pH isn't going to move, but once it gets below 4 you know pH will be dropping pretty soon in a cycling tank, so it serves as an early warning.

~~waterdrop~~

so its normal for the KH to drop as well? My KH had been at 4 after adding the seashells, tested last night and its a definite 3...guess that means I should keep watching the PH then

Yes, as the acids from the nitrification process react with the ions that represent "hardness" the amount of those ions will decrease. Since our KH kits measure "total alkalinity" (as a close correlate of carbonate hardness), that will fall slowly as these reactions occur. The beauty of the KH readings is they serve as a "leading indicator" of what pH will do later.

~~waterdrop~~