Check out this article and determine if you have what people call blossom end rot.

http://counties.cce.cornell.edu/Wyoming/agriculture/resources/ipd/blossom_end_rot/blossom_end_rot.htm

My garden had a problem with it once before and it was because there wasn't enough calcium available in the soil. After I supplemented with some fertilizer rich in calcium the problem went away in a matter of days.

Right, sounds like blossom end rot, which is caused due to a lack of calcium. Check both, calcium content of your nutrient and content of your tap water! (some nutrient are specifically made for soft- and hence calcium rich tap water, or just because they are mono-mixes and can't use any calcium nitrate).

Tomatoes need high calcium, while peppers (especially smaller hot peppers) can cope with lower Ca. Excessive (continuous) vegetative growth, during tomato fruit cycle, due to high nitrogen content, can emphasise the Ca problem. Ca content for tomatos is ideal at 180 PPM while total N-content should be around 140-150 PPM only, and not exceed 150 PPM (by much).

Solving the problem is not an easy task as calcium is one of the lesser mobile elements. It takes time to get to the fruits, even when provided through foliar spray based on calcium chloride (which I recommend though, in case blossom end rot is the real cause)

I think the BER (blossom end rot) is a good call; up your calcium.

One more thing that might do the trick: Grow the peppers apart from the tomatoes; in other words separate them and don't try to grow them together. Tomatoes are heavy feeders and peppers are just the opposite. Also, the peppers may be affecting your nutrient's pH, which in turn may be having a bad effect on the toms.

I'll throw in a link so you can check the EC and pH for each.

Here is a link that might be useful: Growing Tables

Actually you can grow peppers together with tomatoes, if you know how. A PH of 6 will be perfectly fine for both. And, if you know how to compromise with nutrient composition and concentration, it's actually not a difficult task to achieve either.

Mainly because, calcium, magnesium, sulfur and even phosphorus (and to some degree potassium) requirements, are nearly identical. The only thing you need to compromise with is Nitrogen: tomatoes tend to have too vigorous vegetative growth with too high Nitrogen content, while (hot) peppers can use some more. There is a common tendency to think of tomatoes as extra high feeders, but they actually don't need that high concentration in nutrients. I have successfully used a formula developed by the University of Florida which is much lower in concentration, but well balanced instead. This multiple stage formula is pretty suited for peppers too, respectively works just fine when growing peppers together with tomatoes. No wonder It worked perfectly fine in my setup anyway.

A strategy that goes along with high concentrations of nutrients for tomatoes instead, will jeopardize your pepper plants sooner or later. That's a sure thing! And a rather conservative, or let's say very low concentration strategy for hot peppers, will not be sufficient for your tomatoes in the long run either.

Though, for best results (as explained above) it requires the use of self made nutrients, following precise formulas and directions. But alternatively you can also use the data and formulations (see picture) to compare it with available nutrients (if you can).

Explanation: First line In green (French) refers to "from seedling to 1st cluster", second cluster, third, etc. The highest concentration is around 800 PPM, which is nearly perfect for hot peppers.

What I am explaining and showing here is perhaps not exactly what is commonly thought and accepted and it will not necessarily find a large agreement. I don't expect it - but I am convinced of what I am telling, though. Take it or leave it... and don't argue with me, -rather try your luck with the guys @ University of Florida if you like arguing.

Important: Data expressed in simplified NPK DOES NOT refer to actual industrial standard NPK, but to 10x actual PPM. In case you want to compare these values with common NPK values (of commercial products), you need to convert them first!

BER is NOT I repeat NOT due to a Ca deficiency in your nutrient solution.

Its a problem with Ca mobility WITHIN THE PLANT

more Ca will not do anything.

Roma-types are particularly prone to it

High root temps will aggravate it.

BER IS, I repeat BER IS due to lack of Ca in your nutrient, in case your nutrient has NO Ca or very little- and your tap or source water is what we call hard. BER is (in soil culture) classically due to too hot temperatures (not necessarily nutrient temperatures). SUDDEN hot temperatures together with fast growth lead typically to BER, because of low mobility of Ca that cannot follow vigorous growth of foliage and specially fruit development. BER is not very frequent in hydroponics due to better uptake of Ca (while mobility keeps the same). In air conditioned green houses it is rare too. I have grown many tomato varieties hydroponically outdoors under actually very high temperatures and nutrient temperatures (nutes up to 28°C). More or less successfully, I have to say - but WITHOUT any sign of BER.

In case tomatoes suffer under BER, adding Ca to the nutrient solution will not do any change at that stade, right - YET a nutrient solution with the right amount of Ca, will prevent BER, compared to a NS without- or too poor Calcium! SURE THING!

All vigorously growing and prolific types are obviously more prone to BER in case of sudden or persistent heat.

Treatment against BER is difficult because of low mobility of Ca, - as I said, even foliar spray of Ca may be to slow to help - but the only option for a treatment, though.

First, I wouldn't be so quick to assume BER from the little bit of description given. The original poster didn't even say the spots are on the blossom end. Black spots are caused by common fungi like anthracnose and black mold, too. He said the spots appear at ripening. . . which is when anthracnose spots appear. BER will show up on green tomatoes, too. In fact, the few times I've dealt with it I found it on green ones first.

Second, as I was pointing out in other threads (most recently the "New to Hydroponics" one), high solution temps do contribute to BER just as shelbyguy stated. Now, it can be caused by a deficiency in the solution, too, but I'm thinking shelbyguy was pointing out that if you don't have proper temps you can add a gallon of cal-mag and never make a difference. Am I right, shelbyguy?

Here is why high temps cause BER as it was explained to me: Calcium uptake and oxygenation go hand in hand. Higher temps increase root respiration while reducing the oxygen levels. In other words, your plant needs more and has less available. If left unchecked, the roots will greatly reduce uptake. It doesn't matter if you add more oxygen. The water can only hold so much and your roots' needs under high temps will eventually exceed the possible delivery. Obviously, a fruiting plant has a larger root zone and it will be affected faster. Calcium is mainly absorbed by the root tips. Root tips are the first part affected/damaged by poor oxygenation. You do the math. The problem is further exacerbated by changing pH due to the fact that uptake of other nutrients is increased with higher respiration. High pH = calcium precipitation, which leads to it being unavailable even if you fix the temps. So, now you see the downward spiral. Maybe that is why the chiller industry is so successful?

BER is very common in hydro. Don't know why it was said otherwise. It's one of the most common problems because other problems are so largely eliminated. It's more common because it is so easily caused by human error and neglect (like letting the water temps get too high).

Come-on Joe, it really seems that you just insist on your "too high nutrient temps theorie", because you couldn't make your point in the other thread.

BER is not common in Hydroponics with adequate air temperatures, so to speak in green houses and if appropriate nutrients (proven and reliable tomato formulas) are used.

But I anyway hardly understand how subjects are discussed and treated here. I hate to repeat myself over and over again, I actually know pretty well how to argument, but I don't see any sense in it lately. It's not helping anyone!!!

The call about sufficient vs. insufficient Ca content in the nutrient solution was made. The thread starter did not answer or tell about the Ca content. As long as there is no answer to that, we'll never know if this may have caused it or not. If he would check and say: "nope, there is about 180 PPM of Calcium, it can't be the reason!" - I would promptly say: well then I was most probably wrong, let's check other possibilities then...

Now you make the call about nutrient temperature - fine! But if friend "chalfback" isn't going to check his nutrient temperatures, we will not know if this may be the reason of the problem in this particular case either! In case he'd check the temperatures and found it was perfectly fine with 24° C, you could as well drop all of what you have put together here.

I don't get it - I mean this isn't a rhetoric argumentation game for the fun of it, or who might be smarter - or is it at the end? That would actually be a tremendous loss of time and energy, wouldn't it?!

I'm sooooo getting sick of this guy. He obviously didn't read the first paragraph of my post. I don't even think the poster definitely had BER yet jean-luc, once again, is arguing with me over something I didn't say as if I misdiagnosed this problem as BER due to high temps. His BS is bordering on harassment. The only thing that was in response to his posts was about the "BER is not very frequent in hydroponics due to better uptake of Ca", which is false and most of us are well aware of that. I don't think it is a good idea to let such inaccurate statements concerning common issues go unrefuted since people come here to gain knowledge. The rest was in response to Shelbyguy's, Freeman's, and Bilberrybrian's posts and was simply meant to be informative.

I'm not arguing with jean-luc. In fact, I have no desire to deal with him at all. I didn't argue with him here unless you count the very last statement about BER being common in hydro. Not on the "New to Hydroponics" thread, either. The dude is delusional. Look. He even says I made "the call about nutrient temperature." NO I DIDN'T! My call is that I doubt it's even BER based on the description!

Is every thread going to be hijacked with his king of the hill need to rudely speak down to me (and I notice a couple of others, too) and twist what I say into some imaginary argument? Can I not post without risking him ruining the thread just because I might not have the same view as him or I might agree with someone else that opposes his view?

I'm sorry Joe. I feel your pain.
Yes Jean-Luc does appear to be very aggressive in his arguments that every idea besides his are incorrect.
Here's an idea that might help clear the air. how about we just answer the Original posters's(OP) questions and not respond to other peoples responses. Then the OP can decide for himself what he wants to believe after reading all the responses. And ask follow up questions from there.
The exception would be if the OP asks for discussion in his original post.
It would be nice if the gardenweb had forum moderators to control this stuff.
Oh well.

Sympathize, create alliances whatever - and don't worry, my pain is even greater as Mister Joe, manages so smartly to always ambush my explanations and helpful hints from behind - and obviously chasing me through multiple threats to strike back by imposing HIS points to all what I say! Hey Dude, me and hopefully some others are neither stupid nor blind!

You will have all the space and honor of knowing better back pretty soon, I truly have bigger and even nicer pods to fry as arguing with guys who seem to have a severe post traumatic arguing disorder ;-)

Cheers and so long

I's sorry to see you go Jean-Luc. As I've said before, I find the answers you provide very informative. It's a shame y'all (not just you) can't get over berating each other and simply disagree. A lost resource is a terrible casualty here, but at least maybe the place will get back to being civil.