I ran into a problem with my active substrate, so decided to redo my tank and use a HMF. Here's a start of it.
So my Netlea (Similar to ADA) soil, after absorbing all kinds of things from the tank, has decided to start releasing them, so it's time to get rid of it. It's the problem with any active substrate. They have a high CEC and can store things from the water and release them when full. They can also run out of whatever they use to lower the pH. Either way, they do have a lifespan, especially what we want from the soil for shrimp. I am going to reuse it for my planted tank though after a rinse, let it suck up the nutrients I dose and from root tabs.
Mine seems to be loaded with Nitrates and Phosphates. I got algae growing over sponge filters, walls, plants, sponge intakes, rocks, everything. I've taken soil out of the tank, into a container with fresh water, 20-40ppm nitrates within 24 hours. The soil's cap-put.
So I came up with a Hamburg matten filter for my filtration. The tank is a 20gal tank. I'm going to use a bit of inert gravel but leave a big portion of the tank bare bottom for easy cleanup, etc. I am going to use Ebi-ken Sosei, which is a product to lower the pH of your RO water by adding an organic dis solvable fluvic acid that can be added to your RO for water changes and will drop the pH to a acidic range without affect other param's.
Here's the sponge with a dry fit with some supports to hold the sponge in place.
Support rails painted black with Kyrlon paint and siliconed into place.
The idea behind a Hamburg Matten filter is that you put a powerhead or airdriven lift tube behind the sponge, and expelling water out of the area back into the area in front. This forces water to be pulled through the giant wall of sponge. This provides filtration, huge area for biofilm for shrimp, and very low maintenance as the sponge can go sometimes a year or two without being removed and cleaned. The bonus is shrimp love sponges for munching, so bonus for them. Some people even get a bit of moss growing and creeping up the sponge to create a moss wall.
Here's a pic of how the HMF works.
So far I haven't lost any shrimp from the Nitrate/Phosphate dumping but babies sure aren't there like they should. No amount of water changes was able to get rid of it, so I'll see how this method works.
Here's the dry fit for the substrate divider. It's a plastic PVC based compound called Celuka. It's basically the same stuff they use for PVC pipes that's heated and then filled with tiny micro air bubbles then compressed to give a very hard, PVC "wood" that comes in 1x6 and 2x4 and all the standard lumber sizes. It can be cut with a chop shop and comes out with a super smooth edge without sanding, can be drilled, painted, just like wood but just pure PVC. I've used it for turtle docks, crayfish homes, all kinds of things in tanks before and since it's just PVC, just heated with air and no additives, it's safe for tanks like PVC is. I'm going to paint it black and silicone it in so the front part of the tank is bare and can be used for feeding and easy cleanup and the gravel will be contained against the sponge, so it will seal the bottom of the sponge to stop shrimp from crawling under, and act like a UGF and pull crap out of the substrate towards the sponge.
I was also reading Frank say that basically inert soils but ones with a high CEC (He was referring to Akadama) will absorb some of the fluvic acid from the Sosei and release it, thus helping stabilize the ph of water over time as small amounts will be retained and released by the soil. Another reason I choose Flourite black for my substrate.
The other thing with the HMF is you can hide your heater, CO2 difussor, whatever behind the sponge.
Here's the divider glued in and painted.
Painted the bottom of the tank black
I have a fluval 2 internal filter, so I can stuff it with purigen or floss or whatever I want to get a bit of different filtration in there besides the jumbo sponge wall.
Here it is connected to my output that will sit above the water line to get lots of surface movement and O2 exchange. The water rushes through all the holes and slams against them and that should increase O2 content as well as it's creating movement of the return water.
I got some Sosei ordered and should have it in by Tuesday, so I'll see how that works for lowering the pH. I got lots of stuff to load up the tank quickly with biofilm, so it shouldn't take long before I can add some low grades and see how they like it. I think I'd be happy with 6.5pH water for them instead of the 5pH Netlea gives me. Snails don't last long in the low pH, some plants don't like it and as Randy said in another post, it is rather acidic at that pH.
I'm moving in about a year and plan on building a nice shrimp breeding rack, so this is also a test to see if I can get them breeding without active substrate, giant filter wall that doesn't need to be changed or cleaned and something I can add to the water to lower the pH some what. I don't want a rack of 20 tanks with active substrate that need to be replaced, canister filters that need cleaning, etc. Very costly and time consuming to maintain 20 tanks like that. Much easier to have mostly bare bottom tanks, mostly air driven, very little cleaning time, etc.
Thread in the shrimp forum that I'll be keep fairly up to date about the whole procedure.
Active substrate end of life, time for a new tank and idea