Backyard Aquaponics
A place to discuss aquaponics

I've started a new system about 4 weeks ago. I have Gold Fish in my FT, and plants in my GB. My peas beans and corn that were started from seed are looking good, but Tomatoes and Peppers haven't change since they were transplanted. Tested Gravel and when add 12 of the river rock 2 stones fizz a little. PH is about 8.2 and fish are doing fine. Should I replace my grow media?

Patience is needed during the early part of cycling your system. System PH should drift lower as a result of the bacterial action of the nitrification process.

If you remain concerned about your rock effecting you PH then you could do a more substantial test.

Take bucket of rain water and allow it to stand over night. Test PH because it's rain water it should be close to 6 and note the Ph level.
Add a representative sample of the rock being tested to the water and allow to stand over night. Test the water to see if PH has increased and note results.
Allow to stand for two more days and test and note the results.

You should stir up the water a couple of times a day to simulate aquaponic water movement.

This will tell you two things. 1, Whether the sample rock increases PH? and 2, an indication of the strength of the rocks effect on the PH of the system.

If PH goes up from the first test then your rocks effect PH.

If you Ph is substantially higher than 7 on the third test then you may want to change your rocks to something PH neutral. This would be because your rock sample is increasing PH even in and environment that is already above PH neutral.

Many people begin with high PH systems only to see PH drop and then have to add a buffering agent to maintain Ph above dangerously low levels.

A bag of shell grit under a water outlet is a common buffering agent as the acidic water dissolves the calcium from the shell grit and releases it into the system pushing PH higher.

Having said all that if your rock increase Ph but not too bad then you may want to keep them instead of using something like shell grit.

It's a balance thing.
This can seem daunting at first but it's easy with practice.

If it's fizzing when you're doing the vinegar test. You're going to be in for a very hard time getting the PH down.

For the amount of media in an IBC, I'd just dump it and start again. Get some scoria, or a gravel that passes the vinegar test, or clay pebbles. It'll save you a headache down the road.

I tried the rain water retesting the stone and it appears that my PH is still high. I've changed all the media in the GB to knew stone that passes the vinegar test on July 4th. Testing the water and working to lower the PH. Plants seam to be in Nutrient Shutdown.

Welcome Hooten! Peppers are slow to start. Make sure you don't let it fruit too early. Pick the flowers off so the plants can get some good vegetive growth. Once the pepper plant is about a foot high, then let it fruit. Hollar!

I asked that same question because the scoria I used keepsake pH at 8.2. I was about to dump it and start over. Everyone told me not to and to just ride it out. It's been 3 months and my pH is 8.2. I treat all my top up water with hydrochloric acid down to pH of 6. It takes 1 tbspn into 5 gallons of water to do that. It doesn't being my pH down but it does prevent me from adding any more carbonates to the system.

Once my system cycled it is doing fine. Plant growth is good. I need to be better about foliar spraying with iron since that is the opportunity. Fish are happy, bacteria is happy, plants are growing. We had plenty of spinach on the spring. Strawberries are producing every day. Yellow squash is starting to produce as are some of the melons.

In reality, pH is of little concern to me at this point. Bugs are the bigger issue. Killing squash bugs and working to get rid of aphids will help the plants be more productive.