Controlling KH and pH

[killiguy]

I use rainwater for my Apistos but also have a very soft water supply,but its initial pH is 8.5.
I find it easy to get a tank to sit at 4.0 or so with peat extract +-pH down but I have alot of trouble with pH 6.0-6.5.Which I assume is because my water has no buffering capacity.
What is the best thing to use as a buffer ??Bicarb. And how is it best used to stabilize the pH at a given value.
I often have small chunks of limestone rock or shell grit but after a while it looses its effect??covered with organic crud.
I change at least 50% of my water each week.

I forgot to mention I have 100+ tanks so a cheap option is needed

Thanks in advance

 

[jaafaman]

As a direct response to your query, bicarbs do indeed make decent buffers in the 6.5 range, and are also inexpensive for the quantities of water you seek to treat. As to the "organic crud" on your limestone, try mesh bags that you can easily pull and rinse under running water while rolling them between your hands. Remembering that surface area per volume decreases with the size of the chunks, you could place a bit more of the medium-sized pieces and fewer smaller ones to mix sizes and accomplish this "scrubbing" naturally, like a tumbler, without affecting solubility to any appreciable extent.

But you should also consider that PH is but one of the indicators of a system's condition and not necessarily a be-all, end-all center of focus. Buffering itself determines one of the sets of long-term systemic stability, so if your tank lacks the tools for long-term stability the rather obvious approach is to replace the "worn" water with fresh on an increased frequency.

And except for the labor involved (or perhaps due to its focus), water changes are the least costly and more effective way of maintaining the conditions you seek. Operating "a hundred plus" tanks implies that your water distribution tends more toward automation than manual operation, so take a look at how things are set now and try to determine if there's a way to accomplish having more water pass through the setup. Perhaps instead of a single, large change weekly, where conditions are most likely to spike from one set-point to another, two 30% changes during the week, or small but frequent 10-15% changes more often - even daily - might make things "gel" more positively for you. It's a thought, but considering I do not know the full extent of your schedule you may well be in a situation that restricts you to the once weekly.

While you're here, look at the Ca, Mg and hardness thread for a couple of ideas on ways to prep your change water, where you could easily set up a stage in which limestone is subbed for the peat for large holding volumes...

 

[Simon Morgan]

I suggest making up a cheap remineralisation mix.

3 parts Calcium sulphate (aka Gypsum or plaster of paris)
1 part Epsom Salts
1 Part Marine Salt
1/2 part Calcium carbonate (Sold as Limestone flour for Reptiles and birds)

Mix thoroughly and add to water until you get about 100ppm an a TDS meter. If you want more details try some of the specialist Discus sites and forums.

Good luck!

 

[dw1305]

Hi all,
I think Jaafaman has offered a pretty good reply. I'd probably go for "Oyster shell chick grit", as the aragonite form of calcium carbonate is more soluble than calcite. "Sixfoottanks" re-mineralising mix would also work, although I would leave the salt out (NaCl), as I'm not sure what it does. I might add a small amount of potassium bicarbonate (KHCO3) as well. Have a look here for more details <http://www.theplantedtank.co.uk/RO.htm>.

cheers Darrel

 

[jaafaman]

...I'd probably go for "Oyster shell chick grit", as the aragonite form of calcium carbonate is more soluble than calcite. "Sixfoottanks" re-mineralising mix would also work, although I would leave the salt out (NaCl), as I'm not sure what it does. I might add a small amount of potassium bicarbonate (KHCO3) as well. Have a look here for more details <http://www.theplantedtank.co.uk/RO.htm>.

The salt's most likely to get a trace of chlorides in the water, which seems to play a role in low pH, high humic situations and ion exchange at the tissue level in some of the recent studies (one or two pointed out in Chemistry the thread I linked). Sodium chloride seems preferable to potassium in creating a more naturally-ocurring balance.

As to calcite/aragonite, another highly-controllable asset can also be found in Health Food stores as well as the mentioned reptile outlets — finely-ground powders of both calcium carbonate and magnesium carbonate meant as dietary supplements. These are my personal preferences, as I've mentioned previously that I'm liable to keep anything from Amazonia to Lake Tanganyika. Since I'm prone to prep the water ahead of time, there's usually a couple of days for those powders to fully dissolve into solution and the final results double-checked before use...

 

[dw1305]

Hi all,

Sodium chloride seems preferable to potassium in creating a more naturally-ocurring balance.

Ahh got it, that would make sense in animal physiology terms with "signal transduction" and "serum sodium" levels etc. I'd probably keep it in under that arrangement, but possibly reduce the volume.

cheers Darrel