How are your readings now, especially the nitrates?
Harold, nothing has changed. I got a rain barrel set up now (one good rain filled that sucker!) and am using it to top off. I expect it will take a few weeks for the ph to come down, and thus, the nitrates to also come down. I still have only trace amounts of ammonia and nitrites, so that's a good thing. The plant growth is quite impressive, but no fruiting (lots of flowers). The cantaloupe vine is about 15 feet long! I cheated and bought a tomato plant that had already started fruiting, and that's doing well.
Thanks for asking!
Since you're seeing lots of flowers you can add a small amount of potassium to the system this will help to encourage fruiting and fruit growth. Since the pH is on the high side and may not be effective in delivery you can apply it by foliar spraying the specific plant/plants directly.
Adding a bubbler to the FT is also a good idea if you can afford to.There is never a case of having too much oxygen. The higher the DO levels the better a system performs. BTW nice idea with the rain water!
I do have a bubbler which works great! Thanks for the potassium suggestion. I wonder though, that since the majority of the water in the ft is well water, and I do have somewhat hard water, that the ions that cause that are calcium and potassium. So, wouldn't the water have adequate potassium?
The rain barrel suggestion was courtesy of this forum, and TC.
Yes, the water will have potassium as well as what's left over in the fish waste but at high PH it would be difficult for plants to absorb it, if any at all. Fruiting plants require higher amounts of potassium and if they are unable to get it from the water column, we can transport through direct spraying. However your system is a new and fruiting plants usually do better at around 6 month maturity. I did the same and after cycling i put some tomatoes in, they flowered and stood there until about the 6 month mark when i started seeing more rapid growth and fruiting, by the 9th month they really took off. Nitrates grow plants but when plants start fruiting this a sigh of a mature balanced AP system and this takes time!
Actually hard well water is usually more calcium carbonate and magnesium and an overabundance of calcium can actually lock up the potassium a bit. Seaweed extract is a good source of potassium that won't elevate your pH and it can be used as a foliar feed. Potassium bicarbonate might work if you can't get seaweed extract but it will elevate pH but it also happens to be useful as a foliar spray to combat some fungus problems.
I've been collecting rain water for my systems too so that I can reduce my use of well water and the related problems I have with it.