Backyard Aquaponics
A place to discuss aquaponics

Naw better to pee in a bottle and then use it when you can safely see where you are going.

I agree with you TCLynx... it was a "spur of the moment" act.

So.... after almost two weeks of testing the water and waiting for the system to cycle, I got a little frustrated.
The pH has sat at the top limit of my test kit (pH >= 9) without moving. I had thought that it was just town water and that the pH would creep down eventually.

The little plants that got volunteered to test the system all started off well but eventually yellowed and are now looking near death. The little guppies were still doing wel, so I wasn't too worried.

Before going out to find some Hydrochloric acid or similar, I decided to test out my tap water. To my surprise/horror, the pH is at ~7.5 - so something in my system is very alkaline.

The IBCs that I am using had previously stored PVA glue. The tanks were power-washed with soapy water and scrubbed with bleach and then soapy water again. As unlikely as it is, I am leaning towards the IBCs not being 100% clean. I can't think of any other reason why the pH should remain so high.

I'll see if acid will keep it down, as the alternative would be to clean the whole system and starting again.

Your system, pH 9+
Your input water, pH 7.5
Tanks cleaned? Let's say yes, for now.
I didn't read anywhere in the thread so far that you tested the pH of the media?

Take some of your media in a cup and cover it with vinegar or another acidic solution. If the liquid bubbles and fizzes, this is through the acid/base reaction, meaning you have alkaline media ==> problem!

Another test is to put some media in a clean non-reactive container and cover this media with distilled water. Do a pH test straight away, then test again after a few hours, then a few days and then again after a few weeks (if you have the time/patience to wait this long?)

A note for "next time": test the media before purchase, regardless of promises of manufacturers!

If you have alkaline media, you'll have some tough decisions to make as whether you want to ditch the lot and start again, acid flush the media and potentially destroy the structural integrity, or slowly keep adding acids which might end up having the same effect but over a longer timeframe? In any case, your chances of successfully cycling your system with pH>9 are slim, but not completely impossible.

It might be worth completely draining down your system now and doing a 100% water replacement, to try and get the pH at a level when cycling may kick off, a process which will reduce the pH further, or at least compete with the alkalinity? You wont need to empty the media and re-scrub the IBCs... for now.

Thanks for your input bunson. You're right that I hadn't tested my media at all. I was stupid enough to take the manufacturer's word that their expanded clay pebbles were inert and pH neutral. I feel like I have broken an AP commandment.

Unfortunately, my media didn't react to the vinegar at all. No bubbles, large or small. So I am back to square one on this.

I really dread doing a full water-change but it might come to that. Trying to think what to do with all this water

Well... not really sure what to make of this.

Yesterday evening I decide to grasp at straws and do another pH test. The result looked like it was around 8.5 but, I wasn't really sure if it was simply my wishful thinking or not, so I did another test this morning:

pH: 8.0
Ammonia: 2.0
Nitrite: 0.5
Nitrate 2.5

I have done nothing since my desperate posts yesterday. It had not rained or anything....

I am confused but I am not complaining. Let's hope that this is the first sign of the water finally cycling.

Well, pH today seems to be slightly less than 8, but not quite 7.5. At least it's moving in the direction that I want.

pH: (slightly less than) 8
Ammonia: 0
Nitrite: 0.1
Nitrate: 5

I will add some more humonia this evening and see if the system takes care of it, just to be sure.

Then there shall be fish and prawns