Thank you for replying...

Each in its own pot ..

Yes I do water them because they show some signs of drying out ..

Right now they all get some little time in morning sun (very little time)

Maybe the sand is a problem? But understand that you may not have many choices. Fine sand usually clogs up any drainage, so the mix may be still wet even in such hot climate.

Plant in 2nd photo reminds me of Austrocylindropuntia subulata (I don't know if yours is the same plant) and the yellow 'leaves' are ones that fell of it. They will yellow and dry up and fall of as they age, I don't know how many at the same time is considered normal. My plant has very few left right now, I circled couple yellow ones and green ones are only on top:

If I had any doubts, I would put them in little more shade - but you said they are getting only few hours of morning sun (that sounds OK to me).

I think hot and humid would be worse for succulents, but you don't have much humidity, right?

http://forums.gardenweb.com/discussions/1825286/beware-of-the-pencil-cactus?n=112

About the pencil cactus. I think is always good to learn from others before it happens to us.

Wow, I've never experienced temp that high, probably in the low 40s C max. If I may ask, how do you water? Just a bit of water or a lot until the water comes out of the drainage holes? How long does it take for the potting media to dry after thoroughly watering (until excess water comes out of the drainage holes)? They seem really thirsty. And probably need more light too, the growth on the opuntia looks skinny. Is it possible for you to add something gritty (like aquarium gravel/pumice/perlite coarse horticultural sand, whatever available to your area) to your potting media to add aeration? Straight sand surprisingly don't do well for desert plants in containers.

Thank you rina .. we dont have any humidity at all (basicly I live in the desert) your plant does look like mine somehow .. I went to work and found that one of my cactus are wilting and I watered it last night (now its sunset in my time)

It looks so dry and dying ...

And sure roger ill give it a look thanx

I wonder if your pots are not draining. Do you see water run out right away?

This particular one (last pic) I dont see it drain right away ... but the first group of pics yes they do drain

Found some more info -here- (expand for good info on Soil and Watering).

Maybe you should consider repotting: if only sand available, could you sift it using an ordinary kitchen sieve and keep only what stays in the sieve (larger particles)? It will improve drainage. You still need to water often, but it won't 'sit' in wet compacted sand as I suspect it does. Compacted sand is almost like a concrete, water will not penetrate it, just sit around. So the plant may be 'dying of thirst in sea of plenty'...Just speculating here...

We do have the normal planting soil (compost) should I mix that with sand or can I add small pieces or grained rock .. would that help??

Thank you so much for your interest

Can you rig up some shade for them?

All my cactus in the beginning of my post are in shade under a big tree and get some sunshine between the branches for a short period of time..

For the last one my only solution is to put it inside where its around 20 Celsius

You might have to bring them inside for summer, then put them back out when the heat eases.

Some cacti are from relatively high altitudes where they have hot hot hot daytime temperatures and intense sun, but then it cools off dramatically at night so they have a chance to recover. Do your nights cool off?

Its around 38 Celsius at don :)

I was thinking of that from the beginning but I sad to myself.. hey its a cactus it can live outside ..

Using grit would be good, as long as it is not to large; maybe size of aquarium gravel? (can't be sure about size in the photo, it may be slightly large?)

Another thing you could try would be using perlite (if available - I see few grains in the mix you have). If you can get some, add a lot of it to your soil.

hoovb is giving you good advice - the climate/zone 9 is little closer to yours than my zone 5...

I dont think they sell it alone around here it comes with the compost .. ill need to search for it more .. I will ad the smallest grit I can find ...

Thank you so much rina

For grit, many of us buy crushed granite that is fed to chickens, easy to find in farm supply stores around here. Should you be able to find some (make sure it doesn't contain crushed shells), the size #2 is appropriate (#1,smallest is for baby chicks and too small bigger sizes are too large).

Large-grained sand known here as Horticultural sand would be suitable too if available in your location.

Perlite is widely available in many stores in Canada and US, hopefully you can find some.

I will search for that .. things are a lot different in my country.. Thanks for the tip

I am sorry chuckerfly .. I somehow missed your comment..

For watering.. for my cacti I give a little amount because I can see that the soil is not so dry (the soil looks dark and have little moisture).. but for my other plants outside I water them until the water fall from the edge of the pot (it will take a lot of water to come out of the drainage holes because the pot is kinda big and the soil is so dry and I have a lot of plants to water and so little time to do so) and the soil will dry completely after 2 days and the leaves will wilt in the 3rd day ...

And for my opuntia I took the pups to plant them elsewhere.

And I finally fount fishtank gravel (quartz/silica) and I will be repitting all of me cacti soon ...

Thank you all for your help .. I will post some pictures in a week or so to update ..