any ideas?

[kimberfish]

OK I need a bit o help.
I'm having a problem with green algae - doesn't look like HA though it's greenish brown and is only on the glass. I have various crabs that have killed all my snails. (didn't know that would happen).
My phosphates are 0 (salifert) Nitrates +-20(salifert)
265g tank with 4 koralia 4's and a spraybar. 3600gph pump for return and spraybar. Running rowa in a reactor and cheato in the fuge.
feeding every other day. 14 fish in tank (most under 4") skimming with a octopus 200 and am emptying the cup weekly because it's full.
I thought algae needed phosphates to grow so if phosphates are at 0 what gives? I am using ro/di but I don't think it is reading 0 - my tds isn't working right.
I did a 100g wc last week and plan to do another 100g wc today.

[charlie]

I think you may just be running into an algae bloom. The reason you are not reading phosphates is because they are all bound in the algae you have. I don't really think there is a phosphate test kit on the market that is worth a you know what anyways!!!! Is there a way you can get your RO/DI water to a LFS that can give you a separate test? I think you are doing the right thing by doing the water changes, but if your TDS is hosed up...............
The fact is, you an an excess nutrient problem, and you need to find out where it is coming from.

[kimberfish]

took water sample to lfs and I'm reading 15 on tds meter. The unit I was having problems with was reading 132 so this is a huge improvment.
I agree about the phosphates being tied in to the algae.
I'm still not sure where the excess nutrients is from. I really don't think I'm overfeeding. I'll skim a bit wetter this wkend and do my 2nd wc tomorrow...at which time I think I"ll add some marine tank clarifier so it can bind some gunk together allowing it to skim even better.
starting to wonder about my lights - how big of an impact would the bulbs make on the algae? I am changing them out next week so we'll see I guess.
Thanks

[charlie]

15 is still real high for the product water. Try changing your filters on your RO unit, you should see an immediate improvement.
I would stay away from adding anything right now. I find that most of those "tank clarifiers" are BS anyways. I kind of like the natural approach. Keep skimming and let it run it's course, you'll beat it!!!
Worn out bulbs could also cause this, what are you running?

[kimberfish]

I"m running 1 400mh 14k that is 5 months old. About 2 months ago I bought 2 new 250 setups used from a local guy with 2 250watt 12K bulbs - approx 5 months old. But you know how that goes - they are probably older. Next week I plan to get 2 new 250watt 20K xm bulbs as replacements then replace my 400 in Jan.
I'm running 4 48" vhos all blue actinic.... 2 are 1 month old the other 2 are 5 months old
I wouldn't normally use the clarifier either but I have 2 different LFS owners here that swear by it and say they use it in all their maintenance accounts.

thanks for the replies

[Ninong]

I'm having a problem with green algae - doesn't look like HA though it's greenish brown and is only on the glass. I have various crabs that have killed all my snails.

Get more snails. If necessary, remove some or all of the crabs. The snails will eat algal film on the glass, crabs won't/can't. What crabs do you have right now?

For your size tank, you should have at least three dozen nice Trochus snails. If you have a sand bed, you could use a couple dozen Ceriths and at least three dozen Nassarius snails.

My phosphates are 0 (salifert)

Hobby level phosphate kits are not all that great. I have used Salifert's phosphate kit, too, but it can't measure all forms of phosphate. Let's put it this way, your PO4 should be below 0.03 ppm and if your Salifert kit measures it at say .5 or above, you have a problem. Even if you don't measure any at all, you might still have a phosphate problem but I wouldn't blame phosphate if the Salifert kit isn't registering any at all. I would suspect it's probably something else.

I thought algae needed phosphates to grow so if phosphates are at 0 what gives?

Phosphorus is limiting in freshwater environments; nitrogen is limiting in marine environments. To put it another way, nitrogen is more important in marine tanks when it comes to problems with algae. On the other hand, phosphate can cause problems if it is allowed to get out of hand.

Get some snails, keep up the good work with the chaeto and throw away the clarifier.

[kimberfish]

I do want to remove the crabs but other than the occasional sighting is there an easy way to bait/trap them? I'm not sure what all types I have I do know I have one blue leg and one scarlet. I have about 12 nassarius snails.
If I catch the hermits do you think it would be OK to let them live in my fuge? The only other thing in my fuge is a yellow cuke.

[charlie]

Ninong, thanx for the help!!!!!

Let the crabs go in the fuge, if you are anything like me, your fuge is sometimes more interesting than the display. Ever get in there at nite with a flashlite???

[kimberfish]

no I haven't my fuge has only been up and running approx 1 month I'm not sure how much there would be to see yet

[Ninong]

I thought maybe you had something like 50 or more hermit crabs in your tank. If all you have is just a handful, then I wouldn't worry about them. I kept 12 scarlet hermits in my 120-gal tank without any real problems from them. I probably would have done just fine with just three or four but they were cheaper by the dozen.

I did put about a dozen so-called micro-hermits from a vendor in Hawaii into my tank and they were nasty little buggers once they outgrew their "micro" phase. I didn't buy them, he threw them in free and told me they would stay very small. They didn't! They got really big. I removed them by hand every time I saw one. Within a few months, I had removed all of them. I didn't remove any of the scarlets.