Backyard Aquaponics
A place to discuss aquaponics

You'll probably only need to change half the volume so if you got a couple of large containers from walmart or similar to cart & store low ph water. Here our river & rain water is about 6.2 yet town water is 7.4ish. So it's a good idea to have a back up supply for the unexpected. Pete.

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First thing to do is to test your tap water after letting it sit for at least 24 hours - run some into a clean jug or mug and just leave it out and uncovered. The pH reading you've got from it is already high, and the 'true' pH may be even higher because that's what it stabilises at after dissolved gases etc come out of it. Also, can you test your water hardness (tap and system)? Do you get mineral/scale buildup on things? I can't see any on your tank but you might be better than me about cleaning it.

Basically if your supply water has a high pH, your system throughput isn't enough to drop the pH due to nitrification, and you're mostly doing water topups rather than water changes (normal/desirable in aquaponics), your system pH will be pushed higher and higher over time. If your water is really hard, then your system water hardness will increase too, and it will be more difficult to push the pH back down. A pH a long way away from neutral will definitely stress your fish enough to make them stop eating and eventually die; it will also lock out nutrients, leaving your plants unable to use them even if they're in the water.

You need to reduce your system pH gently, or you'll shock your fish and bacteria; aim for less than 0.5 shift per day, 0.3 is better especially to start with. The best way to do this is to get some acid, not the "pH Down" stuff you can get at pet stores, and treat your topup water, not the system itself. There are a bunch of posts from experienced people on here about what sort of acid is best to use and where to get it, I did a quick search but my search engine-fu is poor so hopefully someone will chime in with advice or a link or two. Basically you handle the acid very very carefully, use gloves etc, also it's best to buy a lower concentration; you put your topup water in a big container, dose it down to a pH of about 6.5, and then let it sit for a while again. If your water is hard, the pH will bounce back up and you'll need to add more acid until it's stable. Keep a record of how much acid you need to add to how much water to get the pH correct and you can do it in one go later on; then once it's settled you top up with the treated water and it won't push your system pH up. To get your pH down to a nice comfortable level you probably need to do small water changes with treated water, every day or two, until it's back around 7; then just treating your topup water should be enough to keep it there. (After you've been running your system for a while you may find that the pH starts drifting downwards, in which case you can keep it stable by doing the occasional topup with untreated water.)

If working with acid gives you the heebies or you have nowhere to store and treat your topup water, then bottled water is probably the second best option for you, unless you can work out a way to transport the rainwater! Maybe collect big clean water/juice jugs from friends and family?

Well, I guess I can do things drastically. All the fish have died. None floated to the top after death. Does that mean they arent getting enough air? I dont see how, ive got an air pump with two stones in there as well as the drop from the grow bed. The PH has come down a bit to somewhere in the 8 range. All the other readings are zero. I really dont know what has happeded

Sorry to hear that graz

One of the major contributing factors in my fishes demise was high PH, but any one of the other few conditions could have knocked them off a little later down the track. Apart from some minor issues the GBs were fine and seem to go along with what ever we do to the fish side.

Cycling fishless gives us time to set up our systems to accommodate the plants and more importantly the correct environment for the fish. I am very reluctant to use additives to manipulate my fishes environment because I understand that there could be too many variables and I could end up chasing my tail.

This experience will better prepare you for the next step.

Pete.

That's a bummer graz. A lot of the time fish don't float immediately after they die, they pop up after a day or two if they aren't immediately removed, so them not floating doesn't mean their oxygen was insufficient or anything. (In fact, with goldfish it probably just means they didn't have swim bladder overinflation problems...)

I think the problem is your tap water having a high pH and just pushing things way out of the goldfish's comfort zone. You can keep your plants happy by giving them (small!) doses of liquid fertiliser that contains nitrogen, work out a sustainable fix for your water, and make sure everything is stable before getting more fish.

Im lowering the PH with store water and ill see how things go. Thanks for the tips everybody