Media change out in pool sand filter=mini cycle

skynoch

skynoch

Moderator
So it's been getting harder and harder to keep my nitrates and nitrites down in my 2200 so I've been suspecting my 24" pool sand filter was the problem and just had too much waste in it and the sand was rounding off. Wasn't looking forward to the job as the filter was in the basement and had 100 lbs of sand alone in it. I got the thing opened up and started to use a laddle to get the sand out at first due to the riser pipe in the middle allowing only that much room. I was right the sand was a mess. It took 4 hours to get all the sand out and rinse the filter. I debated wether to only add 1/2 the new sand and rinse 1/2 the old sand but opted on completely new sand since it would take along time to clean out 50 lbs of sand with tank water and swishing. In hindsite I may have been better off trying to rinse out some off the sand since my tank is now in a mini-cycle.
What I'm now wondering is how to prevent this from happening again. It seems my sand is where a major part of the bio is being built up and I'm wondering if my kaldness is maxed out on bio or my sand filter is where the colonies prefered to grow over the kaldness. I don't want to keep any of the old sand do to the fact that it may have rounded off and will not be as effective and also the time to clean it and keep the bio after would be huge.

So my question is would another bio-reactor be best or the addition of another sand filter slowly bypassing it over a time period allowing the other one to colonize more and then changing out the sand. Any thoughts guys?
 
hey scott
im no expert but the stuff that came with my ultima looks like it will last forever!! it has lots of space for bacteria and its really light stuff. i dont think the media can round off. But im no expert..
 
Give your K1 a chance to catch up...

The reason a lot of bacteria was on the sand was for a couple reasons....

One, bacteria doesn't care what it lives on....

Two, it was closest to the food source....

Your bacteria numbers can run out of space to live on though....

Bacteria prefer well oxygenated areas to live on, so the K1 is actually the more preferred place to live on... Although sand beds are also a great place for anaerobic bacteria.

So my advice would be to make them live on it. Don't add the sand back in until you are positive you have enough media to support the load.

What is your filtration anyways?
 
Joey said:
Give your K1 a chance to catch up...

The reason a lot of bacteria was on the sand was for a couple reasons....

One, bacteria doesn't care what it lives on....

Two, it was closest to the food source....

Your bacteria numbers can run out of space to live on though....

Bacteria prefer well oxygenated areas to live on, so the K1 is actually the more preferred place to live on... Although sand beds are also a great place for anaerobic bacteria.

So my advice would be to make them live on it. Don't add the sand back in until you are positive you have enough media to support the load.

What is your filtration anyways?
Click to expand...

I was hoping the k1 was the main area where my bacteria would have flourished but not sure if it or the sand was. I guess I'll know by the length of the mini-cycle on how bad it was. I'm not sure on a pool filter if the sand experiences alot of anaerobic bacteria build up with daily backwashes but I'm sure there was because it just didn't seem to get clean near the end of it's life after a backwash.
I could run my sand pool filter on a recycle mode to bypass the new sand and use filter socks on the outlets for mechanical to see if the k1 will be able to support more bio but I wonder if the sand filter kept running that the allready established k1 would be the first place for new bacteria growth and I could continue to use the sand filter for mechanical?
For filtration now I am running a 6500 gal/hr pump through a 24" pool sand filter for mechanical filtration and then on the return of the filter a small portion goes through a bioreactor back into the tank and the rest goes back into the tank. I also use a 4500 gal/hr pump just for circulation. The bio-reactor and sand filter were added to the tank at the same time I started it up a year and half ago (lol can't remember how long the tanks been running now). I kinda expected the mini-cycle but not sure how to avoid this. Do you think bypassing the sand filter for now would be more beneficial or not?
glamit said:
hey scott
im no expert but the stuff that came with my ultima looks like it will last forever!! it has lots of space for bacteria and its really light stuff. i dont think the media can round off. But im no expert..
Click to expand...

I was debating on replacing the sand with the k1 but decided in the end that the sand (zeosand) would offer a finer filtering than k1. I forget the specs but zeosand is suppose to filter down to 3 microns while normal sand is more like 15 microns and k1 is even higher. In reality you can probably double those numbers for each from what I've gathered from people that have to do the tests so they can meet goverment specs for filtering. In most tanks you would never notice the clarity difference but when a tank is nearly 8' deep you need it as fine as possible. I still may add a second filter either sand or an ultima tho. Your ultima is working good for you?
 
lol....

I answered this question as if you were talking about your substrate ....when you mentioned pool sand filter... i thought you were using it as a substrate..


Either way, the sand filter would have had a lot of bacteria in it... removing it caused the mini cycle like you mentioned.

See if the K1 can make up for it or not... if not, either add more K1, or run the sand filter again.

What are your daily feeding levels?
Total Gallons in system
turn over rate
how much K1 do you have?

what was your flow rate of the k1, compared to the sand?
 
I can add one more cubic foot of k1 to my existing bioreactor and may have to build another or put an ultima filter inline with my 4500 gal/hr circulating pump.
I am running the sand filter again as I need it for my mechanical filtration as this is my main use for it and I sometimes put on filter socks on my filter outputs (socks actually sit in the tank) for extra clarity for photos.
My daily feeding level are around 4 lbs of shrimp and talapia and 1/8 pound of dry food.
My total gallons are 2200
My turnover is around 11000 gal/hr
My sand filter has the 6500 gal/hr pump hooked before it and then after the filter about 50-200 gal/hr go thru the bioreactor (contains the k1). The reason for the difference is I'm seeing if the flowrate is making any difference on the amount of waste the bacteria consumes. And the rest of the flow returns to the tank which might be 4000 gallons counting pressure and head loss.
Sorry if my first posts were unclear.
 
4 cubic feet = about 30 gallons..... 30 gallons = about 113 liters of K1...

K1 is rated at 5 grams of high protein waste per liter of K1.

113 liters of media should be able to handle 565 grams of waste in a 24hr period...

1 pound = 453 grams.

So you have enough to handle a feeding rate of about 1 pound, 4 ounces in a 24hr period...


you dont have enough K1 to handle the load as is.

Even if you add another cubic foot: 7.48gallons or 28 liters.... that would allow for another 140 grams of feeding a day....

For a total of 705 feeding rate allowed in a 24hr period... OR approx 1.5 pounds food a day.


Thats not including the ammonia created by respiration, or urea....

So this is why your in a mini cycle.... you don't have enough k1 to support the load. You'll either have to depend on the sand filter as more than just mech... or have 4 times the K1 you have now.

Although some farms have reported being able to feed up to four times what the media capacity is rated at, and have no issues...


I think your going to keep running into this issue if you continue to run the sand filter...


By the way, 4Lbs of food daily is an enormous amount.. hate to see your monthly food bill!
 
Joey said:
4 cubic feet = about 30 gallons..... 30 gallons = about 113 liters of K1...

K1 is rated at 5 grams of high protein waste per liter of K1.

113 liters of media should be able to handle 565 grams of waste in a 24hr period...

1 pound = 453 grams.

So you have enough to handle a feeding rate of about 1 pound, 4 ounces in a 24hr period...


you dont have enough K1 to handle the load as is.

Even if you add another cubic foot: 7.48gallons or 28 liters.... that would allow for another 140 grams of feeding a day....

For a total of 705 feeding rate allowed in a 24hr period... OR approx 1.5 pounds food a day.


Thats not including the ammonia created by respiration, or urea....

So this is why your in a mini cycle.... you don't have enough k1 to support the load. You'll either have to depend on the sand filter as more than just mech... or have 4 times the K1 you have now.

Although some farms have reported being able to feed up to four times what the media capacity is rated at, and have no issues...


I think your going to keep running into this issue if you continue to run the sand filter...


By the way, 4Lbs of food daily is an enormous amount.. hate to see your monthly food bill!
Click to expand...

Thanks for the help this is exactly what I needed. The mini-cycle is starting to clear up so the k1 couldn't have been to far behind which is amazing for the amount of food and the huge urea/respiratory rate of 11 adult stingrays ranging from 15"-30".
I will for sure have to add another bioreactor to the tank or an ultima. I will be curious once my bio catches up to see how it is working with the new sand and how dirty and worn out my old sand was.
Thanks again Joey
 
hey scott, the ultima is awesome, i havent had any problems at all and im not using any filter socks which could be a problem later on but for now i am really happy with the set up!! thanks again for all your helpcouldnt have done it without u and tim
 
I'm glad to hear the ultima is working out for you. Where did you get yours from? And no problem with the help? :)
 
You must log in or register to reply here.
Back
Top