What's this White Stuff?

[R.K. Castillo]

I've been cycling my system and the last couple of days this white stuff has showed up all over the grow media.  

What is it?

[George]

Conventional wisdom is that you should flood to within two inches of the top of your media, leaving the top two inches dry.  Are you doing that?

[R.K. Castillo]

Yeah...it floods about 2 inches below the top.  But maybe 1 inch of top is dry

[Vlad Jovanovic]

Just some precipitates from your water. Nothing to worry about

They may explain (hopefully at least in part) your apparent non-nitrification related pH drop...as unlikely as that may seem (without some more info)...

[R.K. Castillo]

The same thing happened the last time the PH Dropped and once i did the water change the white stuff left.  

[Vlad Jovanovic]

How fascinating...from what you described, it would seem that your bicarbonates are precipitating out of solution and causing  your pH to drop. Wow. What is the kH (carbonate hardness) of your source water? I'm betting it's pretty low. (Go to the pet store and spend a couple dollars on a kH test kit...get the reagent [liquid drops] and not those stupid totally unreliable paper strips)...

If you haven't already bought that potassium bicarbonate we talked bout earlier, now would probably be a really super-duper good time to that...you really, don't want to just keep using the baking soda (remember that was supposed to be a one time emergency type thing)...

[R.K. Castillo]

Okay will do...how much of the pottassium bicarbonate do you use?

[Vlad Jovanovic]

The amount I will use, and the amount you will use may be 'significantly' different due to our waters different composition. But, roughly 6 grams of potassium bicarb per 50 litres of water should raise kH by about 4dH (which is the same as 71.2ppm).

dH literally means degrees of hardness...it's an old German scale to measure carbonate hardness that is still used today. 1 degree of hardness is equal to about 17.8ppm.

[R.K. Castillo]

So I went to the local hydroponics store and they recommended I use a TDS (Total Dissolved Solids) Meter.  My tap water read 254ppm and the water in my aquaponics system read 489ppm.  

I also got the PH Up and have raised the pH.

What do you think I should do Vlad?  

[Vlad Jovanovic]

"Hey Marge, I couldn't find any aspirin so I bought you these cigarettes..."

You're on your own with those two items buddy...For further instruction, ask the guys that sold them to you. When that doesn't work out, re-read the above posts.

[R.K. Castillo]

So...I take it Carbonate Hardness is not the same as water hardness?  

[R.K. Castillo]

Also the PH Up is the Pottasium Bicarbonate

[Vlad Jovanovic]

Nope. There is carbonate hardness (kH), general hardness (gH)... and total hardness. A kH reading is what you are after.