Blue-Green MADNESS...

First off it sounds like you are adding a large amount of chemicals to the system. I would start by stopping adding all the chemicals, and get down to a basis of where your at by letting it go for a couple weeks to work the chemicals out and test the water, and see what you need to do. Also I would remove the Filter, from what I have read they seem to be a nitrate trap sometimes. I would also switch the filter for a GFO reactor. I have a Biocube 29 and I run a Aqua C skimmer and I add nothing to it and I do have alittle algea but not much. I would also run your RO water through a DI cartridge to make it less PPM 20-30 is still pretty high. That would be my suggestion, also what is the Bioload on the tank.(How many fish)

 

If you do a 5 gallon water exchange every week, you don't have to add anything. Salt mix contains those elements. Don't add what you can't test for. Whats you alk/calcium? Nitrates, do they read 20-30 after your RO or before?

 

What is your tanks nitrate reading?
What is your tanks Phosphate reading?
Are you unsing a DI on your RO system?
What is the TDS reading on the RO water?
How old is the tank?
How many fish?
These would be the starting points to finding your solution. Don't change anything until you know these.
This statement scares me a little "add RO water straight to the system depending on Salinity levels.."
Are you mixing saltwater externally and letting it sit for awhile? The only straight RO you should add to your tank is for top-off to replace evaporation.
Agree with Matt, as a general rule never add anything to your tank you can't measure. Especially to a small system where additions are magnified by small water volume. I also agree in generally getting rid of the Fluval unless you keep it very clean (every couple of days) or are just running carbon or GFO for phosphate removal.
My guess is you have elevated NO3 and PO4, NO3 above 5 or 10 and PO4 above .05. But test it with good kits and get back to us.
Please don't buy any miracle products on the market that will get rid of algae, they will cause more harm than good. We will help you get rid of the reason it is growing, its food: NO3 and PO4.

 

Part of your problem could simply be your canister filter. I have never used one myself but I have read they tend to be more trouble then anything.
I agree with JT. though its food. You said you have 6 fish in your 19 gal, one being a lawnmower blenny and the the other a blue tang, what other fish you got in there? what are you feeding? how much and often?
Stop adding all those chemicals as someone else said.  everything your adding is already in your salt when you do a water change.  and purple up is just calcium.

 

If you are planning to go reef you need to get a 4 stage RO minimum with a DI cannister (Pre, Carbon, RO and DI). This will get you down to 0 TDS (your 0-5 reading is TDS). When the reading goes to 1 you change the DI resin or other filters.
A GFO reactor is for running Granular Ferric Oxide (Rust) and has the sole purpose of removing phosphates. Completely different purpose than what I assume you are running the fluval for which is to remove particulates. Removing particulates in a reef tank is mostly done with filter socks and skimmers.
Nitrates above 0 are food for algae. No more than 20 tells m you probabally need a better test kit. I will guess you are using API, upgrade to one of the reef brands. I prefer Seachem.
Phosphate very low is relative. In the Reef world very low is .01 to .03 with a high range being .05. Only higher precision test kits get down this low. The API Phosphate kit only goes to 1 or .1 if I remember right which is worthless for reefs. If we determine your PO4 is above .05 (I assume it is) then a GFO reactor can fix this but should be done gradually.

 

wouldnt his PO4 read low since the algae is eating it?

 

I personally don't read much into that theory. I am sure it is true when you have a huge amount of algae. I am guessing he doesn't have an appropriate kit to actually measure low PO4, but I could be wrong.

 

well i learned something about my test kits anyway, I use api and I have now found a reason to change. thanks for that.

 

For our purposes the API Calcium is good but not many others go low enough. I really like the Seachem NO3 and PO4 as they are quick and pretty easy to read low concentrations. There was a thread a few weeks ago and many people like Salifert.

 

when you say coral food your talking the stronium essential minerals and such? thats not so much coral food as it is dosing your water. You dont need to do that. as far as spot feeding some do some dont. personally i just feed that tank with rods food and done.

 

Well if your tests are anywhere near accurate you are feeding your algae well. Again Nitrate should be below 5 and near 0, Phosphate should be under .05. But for the future get better test kits that test lower ranges.
On a small system like yours water changes are the fastest way to correct things but not too fast. Also, you have to make sure your replacement water and salt are not putting the nitrates and phosphates back in, so test freshly mixed salt water.
Ways to reduce Nitrate: Water Changes, macro algae in a refugium, DSB (Deep Sand Bed), Nitrate reactor, really good skimmer and carbon dosing.
Ways to reduce Phospahtes: Water changes, GFO Reactor, Carbon Dosing.
Yes Bioballs and such are Nitrate traps and have been dicounted by more modern reef keepers. A DSB (Deep Sand Bed) and Live Rock actually grow Anaerobic bacteria that convert Nitrate into Nitrogen gas which is a good thing, but it does it very slowly as not much water flows through these items.
Just keep the Fluval clean constantly or it will be a problem guaranteed. Most just take them out, I use canisters to polish and remove large particulates but clean the filters every other day.
What you are experiencing is VERY common by the way.

 

I had the same problem with by 29 biocube.  I tried several filters and reactors but with no luck.    Than i read about vodka dosing http://reefkeeping.com/issues/2008-08/nftt/index.php   Now I just run the noraml biocube skimmer and dose once a day.  NO MORE ALGE PROBLEMS!!!

 

Carbon dosing is the new craze and is still new and arguable in the hobby as a whole. Many of our members believe in it and I am close to being in that camp myself. The easy way is with the new bio-pellets but they are expensive. The slightly harder but cheaper way is with Vodka (Sugar and Vinegar are also used by some) but this takes more study and care.
I use Magnum 350 and HOT Magnums, great filters. I have one that is 15 years old and going strong.
Yes on Bio Balls. I also lean towards getting rid of anything that may collect detritus, your rock and sand should be much better bio medias than what you mentioned. But I am not going to reccomend either way on those.
Ya, Seachem Nitrate and Phosphate are reasonable and pretty easy to read. Again, others like Salifert. Seachem is also a Co-sponsor of our MACNA so I say definitely go with them.

 

Maintaining a SW/Reef tank is totally different than a FW.  I'm saying this in a good/nice way, you need to read, read, read and then read some more.  Every tank is different and what works for one, doesn't work for another.  All reefers have their opinions on what works, what doesn't, what's wron and what's right.  You have to decide for yourself and your tank.  There are givens in this hobby like the need to use RO/DI, don't dose what you don't/can't test, maintain proper cal/alk/PH/ etc. levels et cetera.  Your tank is still a "new tank" and tanks go through cycles.  Sometimes trying to correct a problem will create another problem.   Things being said above by others I agree with for the most part...but not the vodka dosing.  Vodka dosing should be a last resort as it is just masking an underlying problem and once used, most 'have to' continue doing it as they haven't attached the true problem.
What and how much are you using for live rock?  It too could be the or part of the problem.  Do you have a sandbed?  What did you use for sand?  This too could be the or part of the problem.  Have you considered the snails are dying from unstable water parameters?  Snails don't do well with fluctuating water params.  The problem that you are having with the algae can be nixed but it may take some time.  Take things slow, read and don't get discouraged.  There is a definite learning curve with SW?reefkeeping.  Help is available here as you can see  from the responses.  I wish you "Happy Reefing"!

 

I will agree with you Terri on everything except the vodka dosing. The jury truly is still out although the results are truly miraculous across the country and they have been carbon dosing in Europe for years. The method as I understand it is not masking the problem but rather feeding larger populations of bacteria that useup excess nutrients. If this is true it wouldn't be masking the problem at all. I just don't want to confuse carbon dosing with things like red slime and algae removers. I will say I think Vodka dosing should be left to the more experienced reefers but from what I know of it bio-pellets can used easily by anyone. People are really getting amazing results. I personally think LED's and carbon dosing are revolutionizing our hobby!
But yet another opinion on whats right or wrong and it is just that my opinion. I agree completely with everything else said though.