pH: how low is too low?

[tomherndon]

Anyone have a quicklink to pH limits on tanks? My 30 long tested out at 6.4 today, which seems fairly low. Neutral gravel, low light, some wood and java ferns. Nitrates were at 10ppm (API master kits.)

Not sure if I should worry about it. I pull a few cups of water from it irregularly and replace with tap/pet bowl water. There's a 50 gallon HOB with sponges inside pulling a fair amount of water through (waterfall sound in playroom is awesome). I haven't hung a cup under the return to determine a rate. I did add a tube to the system to draw water from the other end of the tank ensuring a significant turnover of the tank (never understood why HOB's draw water at the same point as the return.)

The tank is slightly understocked right now and I was testing to see where things were before adding a couple more rasboras to the mix and maybe a few panda cories, they're darn cute.

I'll check the KH shortly and see where things are although I'm fairly certain it'll test VERY low as there are no carbonate sources in the tank.

I'm thinking that if the pH is approaching hazardous, I should be able to buffer it with a couple of boiled seashells (which I have from a summer beach trip).

 

[aqua man]

the ph is not as important as a steady ph. of course you want fish that can tolerate acidic water, but it is more important to have the PH steady then perfect. To answer you question though anything under i would say 5.5 might start being a prob considering
orange juice ia 4 and stomach acid is a 2

 

[SpeedEuphoria]

You want to check the KH and as long as its not 0 you should be OK.

 

[jsoong]

pH less than 5.5 is said to inhibit the bio-filter. People have reported ammonia spikes at those levels .... so that would be one lower limit.

 

[tomherndon]

thanks everyone for the feedback, I'll get the KH tested shortly and if there's zero value, I'll check more articles and solicit some advice.

Does anyone have a thought about adding a seashell or two to introduce the carbonate and help buffer the system. my chem background says that the Ksp of the biologic calcium carbonate will introduce a significant amount of ions initially in that volume and pH and then reach an equilibrium at a higher pH at a fairly slow (not fish shocking) rate.

 

[tomherndon]

I tested the KH and it tested between one and two degrees which translates to between 17 and 34 ppm. Not a lot. If I can't find some data supporting a seashell or two, I may drop a few tums tablets in from time to time to add the calcium, magnesium and carbonate ions to bolster the buffering system in the tank against crashes.

 

[Lager]

Mine is 1 probably a bit less. Don't worry about it. You will not have any crashes as long as you do water changes on a regular basis.

 

[DSenn]

I've been keeping my R.O./tap mix at 1-2 dKH and have had no problems at all. Like lager said, just do water changes and don't overfeed.