Organic fertilizers work really well in the ground, in native soil. They rely on soil microbes to convert the essentially raw materials, fish & sea weed, or bone and blood meal for other kinds, into NPK. Plants can't eat fish, or seaweed, the soil microbes can and they convert the ingredients into nitrogen, potassium, phosphorous, and micro nutrients, that the plants can absorb. Your topsoil mix is very similar to a potting soil, minus the perlite, even with the sandy loam, it probably does not contain the necessary soil microbes to do the converting of the fert you're using. I future years the soil can build up a population of soil microbes and other soil fauna, but this year it's pretty sterile. If I were you, I would use a mild regular fertilizer that is not organic, at least for this year. If you want to continue using organic ferts, you can build up the soil life in the new soil by adding compost and manures, but I would do this in the fall, take a couple months for it to mellow, and not plant during that time. Then every year add some more compost and a little manure at the start of each season, a few weeks before planting, to let it mellow. I

two possibilites: your water has a high calcium level that's acting as a buffer and pulling the pH back up. you plants (yes they're all consuming nutrients if they're growing) are depleting the more acidifying nutrients more quickly than the other nutrients. Nitrogen in particular. In reality, it's probably a combination of both. while 6.7 is not ideal, nothing is blocked from the plants at that level. why don't you just let it be and monitor it for a few days. See how the pH fluctuates and how the plants look. so often with hydro, we see something out of whack from our expectations and are very quick to correct it. sometimes a wait and observe approach is more warranted. what is the pH of the plain water and is it a well or municipal source? if municipal, your provider should be able to provide you with a water report that will tell you what is in the water.

If you haven't asked in the hydroponic growing forums, I'd suggest you try there... the trouble with hydroponics is that it's quite easy to get a nutrient imbalance that you wouldn't get in soil. Another possibility, as you said, is a virus. Single-streak is a combination of two viruses, Potato virus X and Tobacco mosaic virus. It fits your description of mottled leaves, stem lesions, and dark diseased fruit. Both viruses are mechanically transmissible (TMV just by brushing against the leaves)... a good test for virus infection would be to take a healthy soil-grown tomato plant, such as one bought at a nursery, grind up a little of one of the leaves from an infected plant in a couple of tablespoons of water with a pinch of baking soda and fine sand, and rub that solution onto a couple of leaves of the healthy plant. It's not as good as doing it in the proper buffers and such, but both PVX and TMV are so sturdy you have a good chance of getting transmission. If it's viral, you'll get some symptoms within seven to ten days. Pictures would still be helpful, especially if the single-streak pictures don't match what you're seeing. Good luck! --Alison

Consider doing some serious research. Asking people for opinions only gets you opinions which are almost 100% passed back and forth so many times people actually start to think they're facts. You're doing pretty good. You already understand no nitrite means no bacteria. You used the term "total ammonia" too which is good. You're already smarter than the average bear. Let's bump it up one more notch. Lets start with the easy stuff. You don't mention the temperature of the water but I have to assume it's pretty cold. Nitrifying bacteria slow down as the temp drops. At 39F they stop. At 46-50F they only work at 25%. So trying to get a bio filter going is a bit silly in most climates in winter. Moving the fish back to the pond has the same issue, no working bio filter. Moving them back to the pond must work cause that must be a safe place cause millions of ponds overwinter fish without loss. Must because of bio filter...right? Nope. A little harder now is the term "ammonia". When pond people talk about ammonia they almost always think of it a chemical. That's a problem. Ammonia in the pond is 2 chemicals, NH3 and NH4+. They're kind of the same, the difference is just ions. But ions are the thing doing the harm to fish so kind of important to us. What's an ion? Forget about it...not important to us. We only care about how to keep fish safe. There are lots of terms for NH3 such as "free ammonia", "Ammonium hydroxide" and probably what most people just call "ammonia". Let's make it simple and call it "deadly ammonia". This is really what scares us. Lots of terms for NH4+ too "ionized ammonia", "ammonium". Lets call this "safer ammonia" because for fish that's what it is, safe. Most tests are for "Total Ammonia" which of course is the total amount of deadly and safer ammonia. So a total ammonia test by themselves tells you almost nothing when ammonia is detected. There are test kits for telling the difference between deadly and safer ammonia but most people use total ammonia tests. This causes lots of fish deaths as people do all kinds of crazy stuff to lower ammonia...which may have been safe to begin with about now fish are stressed by the "fixes". The weird thing is deadly and safer ammonia go together. You always have both. And they change from one to the other in the blink of the eye as temperature and pH changes. As temp drops "deadly ammonia" converts to "safer ammonia". As pH drops same thing "deadly ammonia" converts to "safer ammonia". As temp and pH go up safer turns into deadly. You've been raising pH, or trying to keep it up, and have been cheered into doing so, to get a bio filter going which probably can't start due to low temps. Keeping the pH up is also busy converting safer ammonia to deadly ammonia. For example there will be about 90 times less deadly ammonia when pH is lower from 8.5 to 6.5 at 68F. By letting water temp fall and letting pH go down the fish can be safe even when total ammonia tests are crazy high. My suggestion is to find a ammonia - ammonium chart on the web you like and use that along with your pH test and water temp to determine first if you have a problem. It's likely you don't have a problem...but are doing things that could cause problems. If you have a problem then water change is the best option imo. Adding an ammonia binder means test results will be meaningless and you'll be flying blind. If needed water changes are often you could consider a 24/7 drip water change. Even with treated city water these can work. I also suggest letting water temp fall to around 40F. Converts most deadly ammonia into safer ammonia and almost stops Aeromonas bacteria from growing. I would not let water stay below say 37-39F for days. Lots of people with froze over ponds think the water temp is near 32F but that's another myth. Fish under ice in a backyard pond are likely enjoying a 39F temp. With an above ground tank the water temp can drop below 39F, even below 32F so you have to keep the temp up a little. Low temp also lowers fish metabolism which reduces ammonia production. Natural selection kind of worked this all out for us...as long as we don't "fix" it. I suggest letting pH fall to wherever it wants to be. You could force pH lower if you really wanted to, knew what you were doing, AND actually had a deadly ammonia issue AND water changes were a problem for some reason. Be really careful of people saying pH should be this or that range. They almost never know what they're talking about and are just repeating what they heard from other repeaters. In reality it's almost impossible for normal water sources to have deadly pH levels. Trying to push pH into some made up range with little understanding is more dangerous. Some other small points...size of the tank doesn't really matter. Sure, bigger the tank the slower ammonia becomes of problem...but it's likely to still be a problem. All the rules of thumb on ratio of water to number/size of fish is a bit silly. Just made up number out of thin air. Fish are kept safe with testing and understanding. Most city water now days don't use chlorine but instead uses chloramine. They sound the same so most people think they're the same and give the same advice they did 20 years ago for chlorine. Chloramine is made by adding ammonia. When we add chemicals to remove "chlorine" that ammonia is released which is why those pond products add an ammonia binder. And why total ammonia tests become useless even with temp & pH charts. Adding binders means you have no idea what's going on ammonia wise in the water unless you have specific tests for the binder.